from __future__ import print_function
# Copyright (C) 2008 CSC - Scientific Computing Ltd.
"""This module defines an ASE interface to VASP.

Developed on the basis of modules by Jussi Enkovaara and John
Kitchin.  The path of the directory containing the pseudopotential
directories (potpaw,potpaw_GGA, potpaw_PBE, ...) should be set
by the environmental flag $VASP_PP_PATH.

The user should also set the environmental flag $VASP_SCRIPT pointing
to a python script looking something like::

   import os
   exitcode = os.system('vasp')

Alternatively, user can set the environmental flag $VASP_COMMAND pointing
to the command use the launch vasp e.g. 'vasp' or 'mpirun -n 16 vasp'

http://cms.mpi.univie.ac.at/vasp/
"""

import os
import sys
import re
from .general import Calculator
from os.path import join, isfile, islink

import numpy as np

import ase
import ase.io
from ase.utils import devnull

from ase.calculators.singlepoint import SinglePointCalculator

# Parameters that can be set in INCAR. The values which are None
# are not written and default parameters of VASP are used for them.

float_keys = [
    'aexx',       # Fraction of exact/DFT exchange
    'aggac',      # Fraction of gradient correction to correlation
    'aggax',      # Fraction of gradient correction to exchange
    'aldac',      # Fraction of LDA correlation energy
    'amin',       #
    'amix',       #
    'amix_mag',   #
    'bmix',       # tags for mixing
    'bmix_mag',   #
    'deper',      # relative stopping criterion for optimization of eigenvalue
    'ebreak',     # absolute stopping criterion for optimization of eigenvalues
                  # (EDIFF/N-BANDS/4)
    'efield',     # applied electrostatic field
    'emax',       # energy-range for DOSCAR file
    'emin',       #
    'enaug',      # Density cutoff
    'encut',      # Planewave cutoff
    'encutgw',    # energy cutoff for response function
    'encutfock',  # FFT grid in the HF related routines
    'hfscreen',   # attribute to change from PBE0 to HSE
    'kspacing',   # determines the number of k-points if the KPOINTS
                  # file is not present. KSPACING is the smallest
                  # allowed spacing between k-points in units of
                  # $\AA$^{-1}$.
    'potim',      # time-step for ion-motion (fs)
    'nelect',     # total number of electrons
    'param1',     # Exchange parameter
    'param2',     # Exchange parameter
    'pomass',     # mass of ions in am
    'pstress',    # add this stress to the stress tensor, and energy E = V *
                  # pstress
    'sigma',      # broadening in eV
    'spring',     # spring constant for NEB
    'time',       # special control tag
    'weimin',     # maximum weight for a band to be considered empty
    'zab_vdw',    # vdW-DF parameter
    'zval',       # ionic valence
    # The next keywords pertain to the VTST add-ons from Graeme Henkelman's
    # group at UT Austin
    'jacobian',   # Weight of lattice to atomic motion
    'ddr',        # (DdR) dimer separation
    'drotmax',    # (DRotMax) number of rotation steps per translation step
    'dfnmin',     # (DFNMin) rotational force below which dimer is not rotated
    'dfnmax',     # (DFNMax) rotational force below which dimer rotation stops
    'stol',       # convergence ratio for minimum eigenvalue
    'sdr',        # finite difference for setting up Lanczos matrix and step
                  # size when translating
    'maxmove',    # Max step for translation for IOPT > 0
    'invcurve',   # Initial curvature for LBFGS (IOPT = 1)
    'timestep',   # Dynamical timestep for IOPT = 3 and IOPT = 7
    'sdalpha',    # Ratio between force and step size for IOPT = 4
    # The next keywords pertain to IOPT = 7 (i.e. FIRE)
    'ftimemax',   # Max time step
    'ftimedec',   # Factor to dec. dt
    'ftimeinc',   # Factor to inc. dt
    'falpha',     # Parameter for velocity damping
    'falphadec',  # Factor to dec. alpha
    'clz',        # electron count for core level shift
    'vdw_radius',  # Cutoff radius for Grimme's DFT-D2 and DFT-D3 and
                   # Tkatchenko and Scheffler's DFT-TS dispersion corrections
    'vdw_scaling',  # Global scaling parameter for Grimme's DFT-D2 dispersion
                    # correction
    'vdw_d',      # Global damping parameter for Grimme's DFT-D2 and Tkatchenko
                  # and Scheffler's DFT-TS dispersion corrections
    'vdw_cnradius',  # Cutoff radius for calculating coordination number in
                    # Grimme's DFT-D3 dispersion correction
    'vdw_s6',     # Damping parameter for Grimme's DFT-D2 and DFT-D3 and
                  # Tkatchenko and Scheffler's DFT-TS dispersion corrections
    'vdw_s8',     # Damping parameter for Grimme's DFT-D3 dispersion correction
    'vdw_sr',     # Scaling parameter for Grimme's DFT-D2 and DFT-D3 and
                  # Tkatchenko and Scheffler's DFT-TS dispersion correction
    'vdw_a1',     # Damping parameter for Grimme's DFT-D3 dispersion correction
    'vdw_a2',     # Damping parameter for Grimme's DFT-D3 dispersion correction
    'eb_k',       # solvent permitivity in Vaspsol
    'tau',        # surface tension parameter in Vaspsol
]

exp_keys = [
    'ediff',      # stopping-criterion for electronic upd.
    'ediffg',     # stopping-criterion for ionic upd.
    'symprec',    # precession in symmetry routines
    # The next keywords pertain to the VTST add-ons from Graeme Henkelman's
    # group at UT Austin
    'fdstep',     # Finite diference step for IOPT = 1 or 2
]

string_keys = [
    'algo',       # algorithm: Normal (Davidson) | Fast | Very_Fast (RMM-DIIS)
    'gga',        # xc-type: PW PB LM or 91
    'metagga',    #
    'prec',       # Precission of calculation (Low, Normal, Accurate)
    'system',     # name of System
    'tebeg',      #
    'teend',      # temperature during run
    'precfock',    # FFT grid in the HF related routines
]

int_keys = [
    'ialgo',      # algorithm: use only 8 (CG) or 48 (RMM-DIIS)
    'ibrion',     # ionic relaxation: 0-MD 1-quasi-New 2-CG
    'icharg',     # charge: 0-WAVECAR 1-CHGCAR 2-atom 10-const
    'idipol',     # monopol/dipol and quadropole corrections
    'images',     # number of images for NEB calculation
    'iniwav',     # initial electr wf. : 0-lowe 1-rand
    'isif',       # calculate stress and what to relax
    'ismear',     # part. occupancies: -5 Blochl -4-tet -1-fermi 0-gaus >0 MP
    'ispin',      # spin-polarized calculation
    'istart',     # startjob: 0-new 1-cont 2-samecut
    'isym',       # symmetry: 0-nonsym 1-usesym 2-usePAWsym
    'iwavpr',     # prediction of wf.: 0-non 1-charg 2-wave 3-comb
    'kpar',       # k-point parallelization paramater
    'ldauprint',  # 0-silent, 1-occ. matrix written to OUTCAR, 2-1+pot. matrix
                  # written
    'ldautype',   # L(S)DA+U: 1-Liechtenstein 2-Dudarev 4-Liechtenstein(LDAU)
    'lmaxmix',    #
    'lorbit',     # create PROOUT
    'maxmix',     #
    'ngx',        # FFT mesh for wavefunctions, x
    'ngxf',       # FFT mesh for charges x
    'ngy',        # FFT mesh for wavefunctions, y
    'ngyf',       # FFT mesh for charges y
    'ngz',        # FFT mesh for wavefunctions, z
    'ngzf',       # FFT mesh for charges z
    'nbands',     # Number of bands
    'nblk',       # blocking for some BLAS calls (Sec. 6.5)
    'nbmod',      # specifies mode for partial charge calculation
    'nelm',       # nr. of electronic steps (default 60)
    'nelmdl',     # nr. of initial electronic steps
    'nelmin',
    'nfree',      # number of steps per DOF when calculting Hessian using
                  # finite differences
    'nkred',      # define sub grid of q-points for HF with
                  # nkredx=nkredy=nkredz
    'nkredx',      # define sub grid of q-points in x direction for HF
    'nkredy',      # define sub grid of q-points in y direction for HF
    'nkredz',      # define sub grid of q-points in z direction for HF
    'nomega',     # number of frequency points
    'nomegar',    # number of frequency points on real axis
    'npar',       # parallelization over bands
    'nsim',       # evaluate NSIM bands simultaneously if using RMM-DIIS
    'nsw',        # number of steps for ionic upd.
    'nupdown',    # fix spin moment to specified value
    'nwrite',     # verbosity write-flag (how much is written)
    'smass',      # Nose mass-parameter (am)
    'vdwgr',      # extra keyword for Andris program
    'vdwrn',      # extra keyword for Andris program
    'voskown',    # use Vosko, Wilk, Nusair interpolation
    # The next keywords pertain to the VTST add-ons from Graeme Henkelman's
    # group at UT Austin
    'ichain',     # Flag for controlling which method is being used (0=NEB,
                  # 1=DynMat, 2=Dimer, 3=Lanczos) if ichain > 3, then both
                  # IBRION and POTIM are automatically set in the INCAR file
    'iopt',       # Controls which optimizer to use.  for iopt > 0, ibrion = 3
                  # and potim = 0.0
    'snl',        # Maximum dimentionality of the Lanczos matrix
    'lbfgsmem',   # Steps saved for inverse Hessian for IOPT = 1 (LBFGS)
    'fnmin',      # Max iter. before adjusting dt and alpha for IOPT = 7 (FIRE)
    'icorelevel',  # core level shifts
    'clnt',       # species index
    'cln',        # main quantum number of excited core electron
    'cll',        # l quantum number of excited core electron
    'ivdw',       # Choose which dispersion correction method to use
    'nbandsgw',   # Number of bands for GW
    'nbandso',    # Number of occupied bands for electron-hole treatment
    'nbandsv',    # Number of virtual bands for electron-hole treatment
    'ncore',      # Number of cores per band, equal to number of cores divided
                  # by npar
    'mdalgo',     # Determines which MD method of Tomas Bucko to use
    'nedos',      # Number of grid points in DOS
]

bool_keys = [
    'addgrid',    # finer grid for augmentation charge density
    'kgamma',     # The generated kpoint grid (from KSPACING) is either
                  # centred at the $\Gamma$
                  # point (e.g. includes the $\Gamma$ point)
                  # (KGAMMA=.TRUE.)
    'laechg',     # write AECCAR0/AECCAR1/AECCAR2
    'lasph',      # non-spherical contributions to XC energy (and pot for
                  # VASP.5.X)
    'lasync',     # overlap communcation with calculations
    'lcharg',     #
    'lcorr',      # Harris-correction to forces
    'ldau',       # L(S)DA+U
    'ldiag',      # algorithm: perform sub space rotation
    'ldipol',     # potential correction mode
    'lelf',       # create ELFCAR
    'lepsilon',   # enables to calculate and to print the BEC tensors
    'lhfcalc',    # switch to turn on Hartree Fock calculations
    'loptics',    # calculate the frequency dependent dielectric matrix
    'lpard',      # evaluate partial (band and/or k-point) decomposed charge
                  # density
    'lplane',     # parallelisation over the FFT grid
    'lscalapack',  # switch off scaLAPACK
    'lscalu',     # switch of LU decomposition
    'lsepb',      # write out partial charge of each band seperately?
    'lsepk',      # write out partial charge of each k-point seperately?
    'lthomas',    #
    'luse_vdw',   # Invoke vdW-DF implementation by Klimes et. al
    'lvdw',   # Invoke DFT-D2 method of Grimme
    'lvhar',      # write Hartree potential to LOCPOT (vasp 5.x)
    'lvtot',      # create WAVECAR/CHGCAR/LOCPOT
    'lwave',      #
    # The next keywords pertain to the VTST add-ons from Graeme Henkelman's
    # group at UT Austin
    'lclimb',     # Turn on CI-NEB
    'ltangentold',  # Old central difference tangent
    'ldneb',      # Turn on modified double nudging
    'lnebcell',   # Turn on SS-NEB
    'lglobal',    # Optmize NEB globally for LBFGS (IOPT = 1)
    'llineopt',   # Use force based line minimizer for translation (IOPT = 1)
    'lbeefens',   # Switch on print of BEE energy contributions in OUTCAR
    'lbeefbas',   # Switch off print of all BEEs in OUTCAR
    'lcalcpol',   # macroscopic polarization (vasp5.2). 'lcalceps'
    'lcalceps',   # Macroscopic dielectric properties and Born effective charge
                  # tensors (vasp 5.2)

    'lvdw',       # Turns on dispersion correction
    'lvdw_ewald',  # Turns on Ewald summation for Grimme's DFT-D2 and
                   # Tkatchenko and Scheffler's DFT-TS dispersion correction
    'lspectral',  # Use the spectral method to calculate independent particle
                  # polarizability
    'lrpa',       # Include local field effects on the Hartree level only
    'lwannier90',  # Switches on the interface between VASP and WANNIER90
    'lsorbit',    # Enable spin-orbit coupling
    'lsol',       # turn on solvation for Vaspsol
]

list_keys = [
    'dipol',      # center of cell for dipol
    'eint',       # energy range to calculate partial charge for
    'ferwe',      # Fixed band occupation (spin-paired)
    'ferdo',      # Fixed band occupation (spin-plarized)
    'iband',      # bands to calculate partial charge for
    'magmom',     # initial magnetic moments
    'kpuse',      # k-point to calculate partial charge for
    'ropt',       # number of grid points for non-local proj in real space
    'rwigs',      # Wigner-Seitz radii
    'ldauu',      # ldau parameters, has potential to redundant w.r.t. dict
    'ldaul',      # key 'ldau_luj', but 'ldau_luj' can't be read direct from
    'ldauj',      # the INCAR (since it needs to know information about atomic
                  # species. In case of conflict 'ldau_luj' gets written out
                  # when a calculation is set up

    'random_seed',  # List of ints used to seed RNG for advanced MD routines
                    # (Bucko)
    'vdw_c6',     # List of floats of C6 parameters (J nm^6 mol^-1) for each
                  # species (DFT-D2 and DFT-TS)
    'vdw_c6au',   # List of floats of C6 parameters (a.u.) for each species
                  # (DFT-TS)
    'vdw_r0',     # List of floats of R0 parameters (angstroms) for each
                  # species (DFT-D2 and DFT-TS)
    'vdw_r0au',   # List of floats of R0 parameters (a.u.) for each species
                  # (DFT-TS)
    'vdw_alpha',  # List of floats of free-atomic polarizabilities for each
                  # species (DFT-TS)
]

special_keys = [
    'lreal',      # non-local projectors in real space
]

dict_keys = [
    'ldau_luj',   # dictionary with L(S)DA+U parameters, e.g. {'Fe':{'L':2,
                  # 'U':4.0, 'J':0.9}, ...}
]

keys = [
    # 'NBLOCK' and KBLOCK       inner block; outer block
    # 'NPACO' and APACO         distance and nr. of slots for P.C.
    # 'WEIMIN, EBREAK, DEPER    special control tags
]


class Vasp(Calculator):
    name = 'Vasp'

    def __init__(self, restart=None,
                 output_template='vasp',
                 track_output=False,
                 **kwargs):
        self.float_params = {}
        self.exp_params = {}
        self.string_params = {}
        self.int_params = {}
        self.bool_params = {}
        self.list_params = {}
        self.special_params = {}
        self.dict_params = {}
        for key in float_keys:
            self.float_params[key] = None
        for key in exp_keys:
            self.exp_params[key] = None
        for key in string_keys:
            self.string_params[key] = None
        for key in int_keys:
            self.int_params[key] = None
        for key in bool_keys:
            self.bool_params[key] = None
        for key in list_keys:
            self.list_params[key] = None
        for key in special_keys:
            self.special_params[key] = None
        for key in dict_keys:
            self.dict_params[key] = None

        # self.string_params['prec'] = 'Normal'

        if kwargs.get('xc', None):
            if kwargs['xc'] not in ['PW91', 'LDA', 'PBE']:
                raise ValueError(
                    '%s not supported for xc! use one of: PW91, LDA or PBE.' %
                    kwargs['xc'])
            # exchange correlation functional
            self.input_params = {'xc': kwargs['xc']}

        else:
            # exchange correlation functional
            self.input_params = {'xc': 'PW91'}

        self.input_params.update({
            'setups': None,    # Special setups (e.g pv, sv, ...)
            'txt': '-',     # Where to send information
            'kpts': (1, 1, 1),  # k-points
            'gamma': False,   # Option to use gamma-sampling instead
                              # of Monkhorst-Pack
            'kpts_nintersections': None,  # number of points between points in
                                          # band structures
            'reciprocal': False,   # Option to write explicit k-points in units
                                   # of reciprocal lattice vectors
            })

        self.restart = restart
        self.track_output = track_output
        self.output_template = output_template
        if restart:
            self.restart_load()
            return

        if (('ldauu' in kwargs)
            and ('ldaul' in kwargs)
            and ('ldauj' in kwargs)
            and ('ldau_luj' in kwargs)):
            raise NotImplementedError(
                'You can either specify ldaul, ldauu, and ldauj OR ldau_luj.'
                'ldau_luj is not a VASP keyword. It is a dictionary that'
                ' specifies'
                'L, U and J for each chemical species in the atoms object. '
                'For example for a water molecule:'
                '''ldau_luj={'H':{'L':2, 'U':4.0, 'J':0.9},
                      'O':{'L':2, 'U':4.0, 'J':0.9}}''')

        self.nbands = self.int_params['nbands']
        self.atoms = None
        self.positions = None
        self.run_counts = 0
        self.set(**kwargs)

    def set(self, **kwargs):
        for key in kwargs:
            if key in self.float_params:
                self.float_params[key] = kwargs[key]
            elif key in self.exp_params:
                self.exp_params[key] = kwargs[key]
            elif key in self.string_params:
                self.string_params[key] = kwargs[key]
            elif key in self.int_params:
                self.int_params[key] = kwargs[key]
            elif key in self.bool_params:
                self.bool_params[key] = kwargs[key]
            elif key in self.list_params:
                self.list_params[key] = kwargs[key]
            elif key in self.special_params:
                self.special_params[key] = kwargs[key]
            elif key in self.dict_params:
                self.dict_params[key] = kwargs[key]
            elif key in self.input_params:
                self.input_params[key] = kwargs[key]
            else:
                raise TypeError('Parameter not defined: ' + key)

    def update(self, atoms):
        if self.calculation_required(atoms, ['energy']):
            if (self.atoms is None or
                self.atoms.positions.shape != atoms.positions.shape):
                # Completely new calculation just reusing the same
                # calculator, so delete any old VASP files found.
                self.clean()
            self.calculate(atoms)

    def initialize(self, atoms):
        """Initialize a VASP calculation

        Constructs the POTCAR file (does not actually write it).
        User should specify the PATH
        to the pseudopotentials in VASP_PP_PATH environment variable

        The pseudopotentials are expected to be in:
        LDA:  $VASP_PP_PATH/potpaw/
        PBE:  $VASP_PP_PATH/potpaw_PBE/
        PW91: $VASP_PP_PATH/potpaw_GGA/

        if your pseudopotentials are somewhere else, or named
        differently you should make symlinks at the paths above that
        point to the right place.
        """

        p = self.input_params

        self.all_symbols = atoms.get_chemical_symbols()
        self.natoms = len(atoms)
        self.spinpol = atoms.get_initial_magnetic_moments().any()
        atomtypes = atoms.get_chemical_symbols()

        # Determine the number of atoms of each atomic species
        # sorted after atomic species
        special_setups = []
        symbols = []
        symbolcount = {}
        if self.input_params['setups']:
            for m in self.input_params['setups']:
                try:
                    special_setups.append(int(m))
                except ValueError:
                    continue

        for m, atom in enumerate(atoms):
            symbol = atom.symbol
            if m in special_setups:
                pass
            else:
                if symbol not in symbols:
                    symbols.append(symbol)
                    symbolcount[symbol] = 1
                else:
                    symbolcount[symbol] += 1

        # Build the sorting list
        self.sort = []
        self.sort.extend(special_setups)

        for symbol in symbols:
            for m, atom in enumerate(atoms):
                if m in special_setups:
                    pass
                else:
                    if atom.symbol == symbol:
                        self.sort.append(m)
        self.resort = list(range(len(self.sort)))
        for n in range(len(self.resort)):
            self.resort[self.sort[n]] = n
        self.atoms_sorted = atoms[self.sort]

        # Check if the necessary POTCAR files exists and
        # create a list of their paths.
        self.symbol_count = []
        for m in special_setups:
            self.symbol_count.append([atomtypes[m], 1])
        for m in symbols:
            self.symbol_count.append([m, symbolcount[m]])

        sys.stdout.flush()
        xc = '/'

        if p['xc'] == 'PW91':
            xc = '_gga/'
        elif p['xc'] == 'PBE':
            xc = '_pbe/'
        if 'VASP_PP_PATH' in os.environ:
            pppaths = os.environ['VASP_PP_PATH'].split(':')
        else:
            pppaths = []
        self.ppp_list = []
        # Setting the pseudopotentials, first special setups and
        # then according to symbols
        for m in special_setups:
            name = 'potpaw' + xc.upper() + p['setups'][str(m)] + '/POTCAR'
            found = False
            for path in pppaths:
                filename = join(path, name)

                if isfile(filename) or islink(filename):
                    found = True
                    self.ppp_list.append(filename)
                    break
                elif isfile(filename + '.Z') or islink(filename + '.Z'):
                    found = True
                    self.ppp_list.append(filename + '.Z')
                    break
            if not found:
                print('Looking for %s' % name)
                raise RuntimeError('No pseudopotential for %s!' % symbol)

        for symbol in symbols:
            try:
                name = 'potpaw' + xc.upper()+symbol + p['setups'][symbol]
            except (TypeError, KeyError):
                name = 'potpaw' + xc.upper() + symbol
            name += '/POTCAR'
            found = False
            for path in pppaths:
                filename = join(path, name)

                if isfile(filename) or islink(filename):
                    found = True
                    self.ppp_list.append(filename)
                    break
                elif isfile(filename + '.Z') or islink(filename + '.Z'):
                    found = True
                    self.ppp_list.append(filename + '.Z')
                    break
            if not found:
                print('''Looking for %s
                The pseudopotentials are expected to be in:
                LDA:  $VASP_PP_PATH/potpaw/
                PBE:  $VASP_PP_PATH/potpaw_PBE/
                PW91: $VASP_PP_PATH/potpaw_GGA/''' % name)
                raise RuntimeError('No pseudopotential for %s!' % symbol)
        self.converged = None
        self.setups_changed = None

    def calculate(self, atoms):
        """Generate necessary files in the working directory and run VASP.

        The method first write VASP input files, then calls the method
        which executes VASP. When the VASP run is finished energy, forces,
        etc. are read from the VASP output.
        """

        # Initialize calculations
        self.initialize(atoms)

        # Write input
        from ase.io.vasp import write_vasp
        write_vasp('POSCAR',
                   self.atoms_sorted,
                   symbol_count=self.symbol_count)
        self.write_incar(atoms)
        self.write_potcar()
        self.write_kpoints()
        self.write_sort_file()

        # Execute VASP
        self.run()
        # Read output
        atoms_sorted = ase.io.read('CONTCAR', format='vasp')
        if self.int_params['ibrion'] > -1 and self.int_params['nsw'] > 0:
            # Update atomic positions and unit cell with the ones read
            # from CONTCAR.
            atoms.positions = atoms_sorted[self.resort].positions
            atoms.cell = atoms_sorted.cell
        self.converged = self.read_convergence()
        self.set_results(atoms)

    def set_results(self, atoms):
        self.read(atoms)
        if self.spinpol:
            self.magnetic_moment = self.read_magnetic_moment()
            if (self.int_params['lorbit'] >= 10
                or (self.int_params['lorbit'] is not None
                    and self.list_params['rwigs'])):
                self.magnetic_moments = self.read_magnetic_moments(atoms)
            else:
                self.magnetic_moments = None
        self.old_float_params = self.float_params.copy()
        self.old_exp_params = self.exp_params.copy()
        self.old_string_params = self.string_params.copy()
        self.old_int_params = self.int_params.copy()
        self.old_input_params = self.input_params.copy()
        self.old_bool_params = self.bool_params.copy()
        self.old_list_params = self.list_params.copy()
        self.old_dict_params = self.dict_params.copy()
        self.atoms = atoms.copy()
        self.name = 'vasp'
        self.version = self.read_version()
        self.niter = self.read_number_of_iterations()
        self.sigma = self.read_electronic_temperature()
        self.nelect = self.read_number_of_electrons()

    def run(self):
        """Method which explicitely runs VASP."""

        if self.track_output:
            self.out = self.output_template + str(self.run_counts) + '.out'
            self.run_counts += 1
        else:
            self.out = self.output_template + '.out'
        stderr = sys.stderr
        p = self.input_params
        if p['txt'] is None:
            sys.stderr = devnull
        elif p['txt'] == '-':
            pass
        elif isinstance(p['txt'], str):
            sys.stderr = open(p['txt'], 'w')
        if 'VASP_COMMAND' in os.environ:
            vasp = os.environ['VASP_COMMAND']
            exitcode = os.system('%s > %s' % (vasp, self.out))
        elif 'VASP_SCRIPT' in os.environ:
            vasp = os.environ['VASP_SCRIPT']
            locals = {}
            exec(compile(open(vasp).read(), vasp, 'exec'), {}, locals)
            exitcode = locals['exitcode']
        else:
            raise RuntimeError('Please set either VASP_COMMAND'
                               ' or VASP_SCRIPT environment variable')
        sys.stderr = stderr
        if exitcode != 0:
            raise RuntimeError('Vasp exited with exit code: %d.  ' % exitcode)

    def restart_load(self):
        """Method which is called upon restart."""
        # Try to read sorting file
        if os.path.isfile('ase-sort.dat'):
            self.sort = []
            self.resort = []
            file = open('ase-sort.dat', 'r')
            lines = file.readlines()
            file.close()
            for line in lines:
                data = line.split()
                self.sort.append(int(data[0]))
                self.resort.append(int(data[1]))
            atoms = ase.io.read('CONTCAR', format='vasp')[self.resort]
        else:
            atoms = ase.io.read('CONTCAR', format='vasp')
            self.sort = list(range(len(atoms)))
            self.resort = list(range(len(atoms)))
        self.atoms = atoms.copy()
        self.read_incar()
        self.read_outcar()
        self.set_results(atoms)
        if not self.float_params['kspacing']:
            self.read_kpoints()
        self.read_potcar()

        self.old_input_params = self.input_params.copy()
        self.converged = self.read_convergence()

    def clean(self):
        """Method which cleans up after a calculation.

        The default files generated by Vasp will be deleted IF this
        method is called.

        """
        files = ['CHG', 'CHGCAR', 'POSCAR', 'INCAR', 'CONTCAR',
                 'DOSCAR', 'EIGENVAL', 'IBZKPT', 'KPOINTS', 'OSZICAR',
                 'OUTCAR', 'PCDAT', 'POTCAR', 'vasprun.xml',
                 'WAVECAR', 'XDATCAR', 'PROCAR', 'ase-sort.dat',
                 'LOCPOT', 'AECCAR0', 'AECCAR1', 'AECCAR2']
        for f in files:
            try:
                os.remove(f)
            except OSError:
                pass

    def set_atoms(self, atoms):
        if (atoms != self.atoms):
            self.converged = None
        self.atoms = atoms.copy()

    def get_atoms(self):
        atoms = self.atoms.copy()
        atoms.set_calculator(self)
        return atoms

    def get_version(self):
        self.update(self.atoms)
        return self.version

    def read_version(self):
        version = None
        for line in open('OUTCAR'):
            if line.find(' vasp.') != -1:  # find the first occurence
                version = line[len(' vasp.'):].split()[0]
                break
        return version

    def get_potential_energy(self, atoms, force_consistent=False):
        self.update(atoms)
        if force_consistent:
            return self.energy_free
        else:
            return self.energy_zero

    def get_number_of_iterations(self):
        self.update(self.atoms)
        return self.niter

    def read_number_of_iterations(self):
        niter = None
        for line in open('OUTCAR'):
            # find the last iteration number
            if line.find('- Iteration') != -1:
                niter = int(line.split(')')[0].split('(')[-1].strip())
        return niter

    def get_electronic_temperature(self):
        self.update(self.atoms)
        return self.sigma

    def read_electronic_temperature(self):
        sigma = None
        for line in open('OUTCAR'):
            if line.find('Fermi-smearing in eV        SIGMA') != -1:
                sigma = float(line.split('=')[1].strip())
        return sigma

    def get_default_number_of_electrons(self, filename='POTCAR'):
        """Get list of tuples (atomic symbol, number of valence electrons)
        for each atomtype from a POTCAR file.  """
        return self.read_default_number_of_electrons(filename)

    def read_default_number_of_electrons(self, filename='POTCAR'):
        nelect = []
        lines = open(filename).readlines()
        for n, line in enumerate(lines):
            if line.find('TITEL') != -1:
                symbol = line.split('=')[1].split()[1].split('_')[0].strip()
                valence = float(lines[n + 4].split(';')[1]
                                .split('=')[1].split()[0].strip())
                nelect.append((symbol, valence))
        return nelect

    def get_number_of_electrons(self):
        self.update(self.atoms)
        return self.nelect

    def read_number_of_electrons(self):
        nelect = None
        for line in open('OUTCAR'):
            if line.find('total number of electrons') != -1:
                nelect = float(line.split('=')[1].split()[0].strip())
        return nelect

    def get_forces(self, atoms):
        self.update(atoms)
        return self.forces

    def get_stress(self, atoms):
        self.update(atoms)
        if self.stress is None:
            raise NotImplementedError
        return self.stress

    def read_stress(self):
        stress = None
        for line in open('OUTCAR'):
            if line.find(' in kB  ') != -1:
                stress = (-np.array([float(a) for a
                                     in line.split()[2:]])[[0, 1, 2, 4, 5, 3]]
                          * 1e-1 * ase.units.GPa)
        return stress

    def read_ldau(self):
        ldau_luj = None
        ldauprint = None
        ldau = None
        ldautype = None
        atomtypes = []
        # read ldau parameters from outcar
        for line in open('OUTCAR'):
            if line.find('TITEL') != -1:    # What atoms are present
                atomtypes.append(line.split()[3].split('_')[0].split('.')[0])
            if line.find('LDAUTYPE') != -1:  # Is this a DFT+U calculation
                ldautype = int(line.split('=')[-1])
                ldau = True
                ldau_luj = {}
            if line.find('LDAUL') != -1:
                L = line.split('=')[-1].split()
            if line.find('LDAUU') != -1:
                U = line.split('=')[-1].split()
            if line.find('LDAUJ') != -1:
                J = line.split('=')[-1].split()
        # create dictionary
        if ldau:
            for i, symbol in enumerate(atomtypes):
                ldau_luj[symbol] = {'L': int(L[i]),
                                    'U': float(U[i]),
                                    'J': float(J[i])}
            self.dict_params['ldau_luj'] = ldau_luj
        return ldau, ldauprint, ldautype, ldau_luj

    def calculation_required(self, atoms, quantities):
        if (self.positions is None or
            (self.atoms != atoms) or
            (self.float_params != self.old_float_params) or
            (self.exp_params != self.old_exp_params) or
            (self.string_params != self.old_string_params) or
            (self.int_params != self.old_int_params) or
            (self.bool_params != self.old_bool_params) or
            (self.list_params != self.old_list_params) or
            (self.input_params != self.old_input_params) or
            (self.dict_params != self.old_dict_params)
            or not self.converged):
            return True
        if 'magmom' in quantities:
            return not hasattr(self, 'magnetic_moment')
        return False

    def get_number_of_bands(self):
        return self.nbands

    def get_k_point_weights(self):
        self.update(self.atoms)
        return self.read_k_point_weights()

    def get_number_of_spins(self):
        if self.spinpol is None:
            return 1
        else:
            return 1 + int(self.spinpol)

    def get_eigenvalues(self, kpt=0, spin=0):
        self.update(self.atoms)
        return self.read_eigenvalues(kpt, spin)

    def get_occupation_numbers(self, kpt=0, spin=0):
        self.update(self.atoms)
        return self.read_occupation_numbers(kpt, spin)

    def get_fermi_level(self):
        return self.fermi

    def get_number_of_grid_points(self):
        raise NotImplementedError

    def get_pseudo_density(self):
        raise NotImplementedError

    def get_pseudo_wavefunction(self, n=0, k=0, s=0, pad=True):
        raise NotImplementedError

    def get_bz_k_points(self):
        raise NotImplementedError

    def get_ibz_kpoints(self):
        self.update(self.atoms)
        return self.read_ibz_kpoints()

    def get_ibz_k_points(self):
        return self.get_ibz_kpoints()

    def get_spin_polarized(self):
        if not hasattr(self, 'spinpol'):
            self.spinpol = self.atoms.get_initial_magnetic_moments().any()
        return self.spinpol

    def get_magnetic_moment(self, atoms):
        self.update(atoms)
        return self.magnetic_moment

    def get_magnetic_moments(self, atoms):
        if self.int_params['lorbit'] >= 10 or self.list_params['rwigs']:
            self.update(atoms)
            return self.magnetic_moments
        else:
            return None

    def get_dipole_moment(self, atoms):
        """Returns total dipole moment of the system."""
        self.update(atoms)
        return self.dipole

    def get_xc_functional(self):
        return self.input_params['xc']

    def write_incar(self, atoms, **kwargs):
        """Writes the INCAR file."""
        # jrk 1/23/2015 I added this flag because this function has
        # two places where magmoms get written. There is some
        # complication when restarting that often leads to magmom
        # getting written twice. this flag prevents that issue.
        magmom_written = False
        incar = open('INCAR', 'w')
        incar.write('INCAR created by Atomic Simulation Environment\n')
        for key, val in self.float_params.items():
            if val is not None:
                incar.write(' %s = %5.6f\n' % (key.upper(), val))
        for key, val in self.exp_params.items():
            if val is not None:
                incar.write(' %s = %5.2e\n' % (key.upper(), val))
        for key, val in self.string_params.items():
            if val is not None:
                incar.write(' %s = %s\n' % (key.upper(), val))
        for key, val in self.int_params.items():
            if val is not None:
                incar.write(' %s = %d\n' % (key.upper(), val))
                if key == 'ichain' and val > 0:
                    incar.write(' IBRION = 3\n POTIM = 0.0\n')
                    for key, val in self.int_params.items():
                        if key == 'iopt' and val is None:
                            print('WARNING: optimization is '
                                  'set to LFBGS (IOPT = 1)')
                            incar.write(' IOPT = 1\n')
                    for key, val in self.exp_params.items():
                        if key == 'ediffg' and val is None:
                            RuntimeError('Please set EDIFFG < 0')
        for key, val in self.list_params.items():
            if val is not None:
                if key in ('dipol', 'eint', 'ropt', 'rwigs'):
                    incar.write(' %s = ' % key.upper())
                    [incar.write('%.4f ' % x) for x in val]
                # ldau_luj is a dictionary that encodes all the
                # data. It is not a vasp keyword. An alternative to
                # the dictionary is to to use 'ldauu', 'ldauj',
                # 'ldaul', which are vasp keywords.
                elif key in ('ldauu', 'ldauj') and \
                    self.dict_params['ldau_luj'] is None:
                    incar.write(' %s = ' % key.upper())
                    [incar.write('%.4f ' % x) for x in val]
                elif key in ('ldaul') and \
                    self.dict_params['ldau_luj'] is None:
                    incar.write(' %s = ' % key.upper())
                    [incar.write('%d ' % x) for x in val]
                elif key in ('ferwe', 'ferdo'):
                    incar.write(' %s = ' % key.upper())
                    [incar.write('%.1f ' % x) for x in val]
                elif key in ('iband', 'kpuse'):
                    incar.write(' %s = ' % key.upper())
                    [incar.write('%i ' % x) for x in val]
                elif key == 'magmom':
                    incar.write(' %s = ' % key.upper())
                    magmom_written = True
                    list = [[1, val[0]]]
                    for n in range(1, len(val)):
                        if val[n] == val[n - 1]:
                            list[-1][0] += 1
                        else:
                            list.append([1, val[n]])
                    [incar.write('%i*%.4f ' % (mom[0],
                                               mom[1]))
                     for mom in list]
                incar.write('\n')
        for key, val in self.bool_params.items():
            if val is not None:
                incar.write(' %s = ' % key.upper())
                if val:
                    incar.write('.TRUE.\n')
                else:
                    incar.write('.FALSE.\n')
        for key, val in self.special_params.items():
            if val is not None:
                incar.write(' %s = ' % key.upper())
                if key == 'lreal':
                    if isinstance(val, str):
                        incar.write(val + '\n')
                    elif isinstance(val, bool):
                        if val:
                            incar.write('.TRUE.\n')
                        else:
                            incar.write('.FALSE.\n')
        for key, val in self.dict_params.items():
            if val is not None:
                if key == 'ldau_luj':
                    llist = ulist = jlist = ''
                    for symbol in self.symbol_count:
                        #  default: No +U
                        luj = val.get(symbol[0], {'L': -1, 'U': 0.0, 'J': 0.0})
                        llist += ' %i' % luj['L']
                        ulist += ' %.3f' % luj['U']
                        jlist += ' %.3f' % luj['J']
                    incar.write(' LDAUL =%s\n' % llist)
                    incar.write(' LDAUU =%s\n' % ulist)
                    incar.write(' LDAUJ =%s\n' % jlist)

        if self.spinpol and not magmom_written:
            if not self.int_params['ispin']:
                incar.write(' ispin = 2\n'.upper())
            # Write out initial magnetic moments
            magmom = atoms.get_initial_magnetic_moments()[self.sort]
            list = [[1, magmom[0]]]
            for n in range(1, len(magmom)):
                if magmom[n] == magmom[n - 1]:
                    list[-1][0] += 1
                else:
                    list.append([1, magmom[n]])
            incar.write(' magmom = '.upper())
            [incar.write('%i*%.4f ' % (mom[0], mom[1])) for mom in list]
            incar.write('\n')
        incar.close()

    def write_kpoints(self, **kwargs):
        """Writes the KPOINTS file."""
        p = self.input_params
        kpoints = open('KPOINTS', 'w')
        kpoints.write('KPOINTS created by Atomic Simulation Environment\n')
        shape = np.array(p['kpts']).shape
        if len(shape) == 1:
            kpoints.write('0\n')
            if p['gamma']:
                kpoints.write('Gamma\n')
            else:
                kpoints.write('Monkhorst-Pack\n')
            [kpoints.write('%i ' % kpt) for kpt in p['kpts']]
            kpoints.write('\n0 0 0\n')
        elif len(shape) == 2:
            kpoints.write('%i \n' % (len(p['kpts'])))
            if p['reciprocal']:
                kpoints.write('Reciprocal\n')
            else:
                kpoints.write('Cartesian\n')
            for n in range(len(p['kpts'])):
                [kpoints.write('%f ' % kpt) for kpt in p['kpts'][n]]
                if shape[1] == 4:
                    kpoints.write('\n')
                elif shape[1] == 3:
                    kpoints.write('1.0 \n')
        kpoints.close()

    def write_potcar(self, suffix=""):
        """Writes the POTCAR file."""
        import tempfile
        potfile = open('POTCAR' + suffix, 'w')
        for filename in self.ppp_list:
            if filename.endswith('R'):
                for line in open(filename, 'r'):
                    potfile.write(line)
            elif filename.endswith('.Z'):
                file_tmp = tempfile.NamedTemporaryFile()
                os.system('gunzip -c %s > %s' % (filename, file_tmp.name))
                for line in file_tmp.readlines():
                    potfile.write(line)
                file_tmp.close()
        potfile.close()

    def write_sort_file(self):
        """Writes a sortings file.

        This file contains information about how the atoms are sorted in
        the first column and how they should be resorted in the second
        column. It is used for restart purposes to get sorting right
        when reading in an old calculation to ASE."""

        file = open('ase-sort.dat', 'w')
        for n in range(len(self.sort)):
            file.write('%5i %5i \n' % (self.sort[n], self.resort[n]))

    # Methods for reading information from OUTCAR files:
    def read_energy(self, all=None):
        [energy_free, energy_zero] = [0, 0]
        if all:
            energy_free = []
            energy_zero = []
        for line in open('OUTCAR', 'r'):
            # Free energy
            if line.lower().startswith('  free  energy   toten'):
                if all:
                    energy_free.append(float(line.split()[-2]))
                else:
                    energy_free = float(line.split()[-2])
            # Extrapolated zero point energy
            if line.startswith('  energy  without entropy'):
                if all:
                    energy_zero.append(float(line.split()[-1]))
                else:
                    energy_zero = float(line.split()[-1])
        return [energy_free, energy_zero]

    def read_forces(self, atoms, all=False):
        """Method that reads forces from OUTCAR file.

        If 'all' is switched on, the forces for all ionic steps
        in the OUTCAR file be returned, in other case only the
        forces for the last ionic configuration is returned."""

        file = open('OUTCAR', 'r')
        lines = file.readlines()
        file.close()
        n = 0
        if all:
            all_forces = []
        for line in lines:
            if line.rfind('TOTAL-FORCE') > -1:
                forces = []
                for i in range(len(atoms)):
                    forces.append(np.array([float(f) for f in
                                            lines[n + 2 + i].split()[3:6]]))
                if all:
                    all_forces.append(np.array(forces)[self.resort])
            n += 1
        if all:
            return np.array(all_forces)
        else:
            return np.array(forces)[self.resort]

    def read_fermi(self):
        """Method that reads Fermi energy from OUTCAR file"""
        E_f = None
        for line in open('OUTCAR', 'r'):
            if line.rfind('E-fermi') > -1:
                E_f = float(line.split()[2])
        return E_f

    def read_dipole(self):
        dipolemoment = np.zeros([1, 3])
        for line in open('OUTCAR', 'r'):
            if line.rfind('dipolmoment') > -1:
                dipolemoment = np.array([float(f) for f in line.split()[1:4]])
        return dipolemoment

    def read_magnetic_moments(self, atoms):
        magnetic_moments = np.zeros(len(atoms))
        n = 0
        lines = open('OUTCAR', 'r').readlines()
        for line in lines:
            if line.rfind('magnetization (x)') > -1:
                for m in range(len(atoms)):
                    magnetic_moments[m] = float(lines[n + m + 4].split()[4])
            n += 1
        return np.array(magnetic_moments)[self.resort]

    def read_magnetic_moment(self):
        n = 0
        for line in open('OUTCAR', 'r'):
            if line.rfind('number of electron  ') > -1:
                magnetic_moment = float(line.split()[-1])
            n += 1
        return magnetic_moment

    def read_nbands(self):
        for line in open('OUTCAR', 'r'):
            line = self.strip_warnings(line)
            if line.rfind('NBANDS') > -1:
                return int(line.split()[-1])

    def strip_warnings(self, line):
        """Returns empty string instead of line from warnings in OUTCAR."""
        if line[0] == "|":
            return ""
        else:
            return line

    def read_convergence(self):
        """Method that checks whether a calculation has converged."""
        converged = None
        # First check electronic convergence
        for line in open('OUTCAR', 'r'):
            if 0:  # vasp always prints that!
                if line.rfind('aborting loop') > -1:  # scf failed
                    raise RuntimeError(line.strip())
                    break
            if line.rfind('EDIFF  ') > -1:
                ediff = float(line.split()[2])
            if line.rfind('total energy-change') > -1:
                # I saw this in an atomic oxygen calculation. it
                # breaks this code, so I am checking for it here.
                if 'MIXING' in line:
                    continue
                split = line.split(':')
                a = float(split[1].split('(')[0])
                b = split[1].split('(')[1][0:-2]
                # sometimes this line looks like (second number wrong format!):
                # energy-change (2. order) :-0.2141803E-08  ( 0.2737684-111)
                # we are checking still the first number so
                # let's "fix" the format for the second one
                if 'e' not in b.lower():
                    # replace last occurence of - (assumed exponent) with -e
                    bsplit = b.split('-')
                    bsplit[-1] = 'e' + bsplit[-1]
                    b = '-'.join(bsplit).replace('-e', 'e-')
                b = float(b)
                if [abs(a), abs(b)] < [ediff, ediff]:
                    converged = True
                else:
                    converged = False
                    continue
        # Then if ibrion in [1,2,3] check whether ionic relaxation
        # condition been fulfilled
        if (self.int_params['ibrion'] in [1, 2, 3]
            and self.int_params['nsw'] not in [0]):
            if not self.read_relaxed():
                converged = False
            else:
                converged = True
        return converged

    def read_ibz_kpoints(self):
        lines = open('OUTCAR', 'r').readlines()
        ibz_kpts = []
        n = 0
        i = 0
        for line in lines:
            if line.rfind('Following cartesian coordinates') > -1:
                m = n + 2
                while i == 0:
                    ibz_kpts.append([float(lines[m].split()[p])
                                     for p in range(3)])
                    m += 1
                    if lines[m] == ' \n':
                        i = 1
            if i == 1:
                continue
            n += 1
        ibz_kpts = np.array(ibz_kpts)
        return np.array(ibz_kpts)

    def read_k_point_weights(self):
        file = open('IBZKPT')
        lines = file.readlines()
        file.close()
        if 'Tetrahedra\n' in lines:
            N = lines.index('Tetrahedra\n')
        else:
            N = len(lines)
        kpt_weights = []
        for n in range(3, N):
            kpt_weights.append(float(lines[n].split()[3]))
        kpt_weights = np.array(kpt_weights)
        kpt_weights /= np.sum(kpt_weights)
        return kpt_weights

    def read_eigenvalues(self, kpt=0, spin=0):
        file = open('EIGENVAL', 'r')
        lines = file.readlines()
        file.close()
        eigs = []
        for n in range(8 + kpt * (self.nbands + 2),
                       8 + kpt * (self.nbands + 2) + self.nbands):
            eigs.append(float(lines[n].split()[spin + 1]))
        return np.array(eigs)

    def read_occupation_numbers(self, kpt=0, spin=0):
        lines = open('OUTCAR').readlines()
        nspins = self.get_number_of_spins()
        start = 0
        if nspins == 1:
            for n, line in enumerate(lines):  # find it in the last iteration
                m = re.search(' k-point *' + str(kpt + 1)+' *:', line)
                if m is not None:
                    start = n
        else:
            for n, line in enumerate(lines):
                # find it in the last iteration
                if line.find(' spin component ' + str(spin + 1)) != -1:
                    start = n
            for n2, line2 in enumerate(lines[start:]):
                m = re.search(' k-point *' + str(kpt + 1) + ' *:', line2)
                if m is not None:
                    start = start + n2
                    break
        for n2, line2 in enumerate(lines[start + 2:]):
            if not line2.strip():
                break
        occ = []
        for line in lines[start + 2:start + 2 + n2]:
            occ.append(float(line.split()[2]))
        return np.array(occ)

    def read_relaxed(self):
        for line in open('OUTCAR', 'r'):
            if line.rfind('reached required accuracy') > -1:
                return True
        return False

# The below functions are used to restart a calculation and are under early
# constructions

    def read_incar(self, filename='INCAR'):
        """Method that imports settings from INCAR file."""

        self.spinpol = False
        file = open(filename, 'r')
        file.readline()
        lines = file.readlines()
        for line in lines:
            try:
                # Make multiplication, comments, and parameters easier to spot
                line = line.replace("*", " * ")
                line = line.replace("=", " = ")
                line = line.replace("#", "# ")
                data = line.split()
                # Skip empty and commented lines.
                if len(data) == 0:
                    continue
                elif data[0][0] in ['#', '!']:
                    continue
                key = data[0].lower()
                if key in float_keys:
                    self.float_params[key] = float(data[2])
                elif key in exp_keys:
                    self.exp_params[key] = float(data[2])
                elif key in string_keys:
                    self.string_params[key] = str(data[2])
                elif key in int_keys:
                    if key == 'ispin':
                        # JRK added. not sure why we would want to leave ispin
                        # out
                        self.int_params[key] = int(data[2])
                        if int(data[2]) == 2:
                            self.spinpol = True
                    else:
                        self.int_params[key] = int(data[2])
                elif key in bool_keys:
                    if 'true' in data[2].lower():
                        self.bool_params[key] = True
                    elif 'false' in data[2].lower():
                        self.bool_params[key] = False
                elif key in list_keys:
                    list = []
                    if key in ('dipol', 'eint', 'ferwe', 'ferdo',
                               'ropt', 'rwigs',
                               'ldauu', 'ldaul', 'ldauj'):
                        for a in data[2:]:
                            if a in ["!", "#"]:
                                break
                            list.append(float(a))
                    elif key in ('iband', 'kpuse'):
                        for a in data[2:]:
                            if a in ["!", "#"]:
                                break
                            list.append(int(a))
                    self.list_params[key] = list
                    if key == 'magmom':
                        list = []
                        i = 2
                        while i < len(data):
                            if data[i] in ["#", "!"]:
                                break
                            if data[i] == "*":
                                b = list.pop()
                                i += 1
                                for j in range(int(b)):
                                    list.append(float(data[i]))
                            else:
                                list.append(float(data[i]))
                            i += 1
                        self.list_params['magmom'] = list
                        list = np.array(list)
                        if self.atoms is not None:
                            self.atoms.set_initial_magnetic_moments(
                                list[self.resort])
                elif key in special_keys:
                    if key == 'lreal':
                        if 'true' in data[2].lower():
                            self.special_params[key] = True
                        elif 'false' in data[2].lower():
                            self.special_params[key] = False
                        else:
                            self.special_params[key] = data[2]
            except KeyError:
                raise IOError('Keyword "%s" in INCAR is'
                              'not known by calculator.' % key)
            except IndexError:
                raise IOError('Value missing for keyword "%s".' % key)

    def read_outcar(self):
        # Spin polarized calculation?
        file = open('OUTCAR', 'r')
        lines = file.readlines()
        file.close()
        for line in lines:
            if line.rfind('ISPIN') > -1:
                if int(line.split()[2]) == 2:
                    self.spinpol = True
                else:
                    self.spinpol = None
        self.energy_free, self.energy_zero = self.read_energy()
        self.forces = self.read_forces(self.atoms)
        self.dipole = self.read_dipole()
        self.fermi = self.read_fermi()
        self.stress = self.read_stress()
        self.nbands = self.read_nbands()
        self.read_ldau()
        p = self.int_params
        q = self.list_params
        if self.spinpol:
            self.magnetic_moment = self.read_magnetic_moment()
            if p['lorbit'] >= 10 or (p['lorbit'] is None and q['rwigs']):
                self.magnetic_moments = self.read_magnetic_moments(self.atoms)
            else:
                self.magnetic_moments = None
        self.set(nbands=self.nbands)

    def read_kpoints(self, filename='KPOINTS'):
        file = open(filename, 'r')
        lines = file.readlines()
        file.close()
        ktype = lines[2].split()[0].lower()[0]
        if ktype in ['g', 'm']:
            if ktype == 'g':
                self.set(gamma=True)
            kpts = np.array([int(lines[3].split()[i]) for i in range(3)])
            self.set(kpts=kpts)
        elif ktype in ['c', 'k']:
            raise NotImplementedError('Only Monkhorst-Pack and gamma centered'
                                      ' grid supported for restart.')
        else:
            raise NotImplementedError('Only Monkhorst-Pack and gamma centered '
                                      'grid supported for restart.')

    def read_potcar(self):
        """ Method that reads the Exchange Correlation functional from POTCAR file.
        """
        file = open('POTCAR', 'r')
        lines = file.readlines()
        file.close()

        # Search for key 'LEXCH' in POTCAR
        xc_flag = None
        for line in lines:
            key = line.split()[0].upper()
            if key == 'LEXCH':
                xc_flag = line.split()[-1].upper()
                break

        if xc_flag is None:
            raise ValueError('LEXCH flag not found in POTCAR file.')

        # Values of parameter LEXCH and corresponding XC-functional
        xc_dict = {'PE': 'PBE', '91': 'PW91', 'CA': 'LDA'}

        if xc_flag not in xc_dict.keys():
            raise ValueError('Unknown xc-functional flag found in POTCAR,'
                             ' LEXCH=%s' % xc_flag)

        self.input_params['xc'] = xc_dict[xc_flag]

    def get_nonselfconsistent_energies(self, bee_type):
        """ Method that reads and returns BEE energy contributions
            written in OUTCAR file.
        """
        assert bee_type == 'beefvdw'
        cmd = 'grep -32 "BEEF xc energy contributions" OUTCAR | tail -32'
        p = os.popen(cmd,
                     'r')
        s = p.readlines()
        p.close()
        xc = np.array([])
        for i, l in enumerate(s):
            l_ = float(l.split(":")[-1])
            xc = np.append(xc, l_)
        assert len(xc) == 32
        return xc


class VaspChargeDensity(object):
    """Class for representing VASP charge density"""

    def __init__(self, filename='CHG'):
        # Instance variables
        self.atoms = []   # List of Atoms objects
        self.chg = []     # Charge density
        self.chgdiff = []  # Charge density difference, if spin polarized
        self.aug = ''     # Augmentation charges, not parsed just a big string
        self.augdiff = ''  # Augmentation charge differece, is spin polarized

        # Note that the augmentation charge is not a list, since they
        # are needed only for CHGCAR files which store only a single
        # image.
        if filename is not None:
            self.read(filename)

    def is_spin_polarized(self):
        if len(self.chgdiff) > 0:
            return True
        return False

    def _read_chg(self, fobj, chg, volume):
        """Read charge from file object

        Utility method for reading the actual charge density (or
        charge density difference) from a file object. On input, the
        file object must be at the beginning of the charge block, on
        output the file position will be left at the end of the
        block. The chg array must be of the correct dimensions.

        """
        # VASP writes charge density as
        # WRITE(IU,FORM) (((C(NX,NY,NZ),NX=1,NGXC),NY=1,NGYZ),NZ=1,NGZC)
        # Fortran nested implied do loops; innermost index fastest
        # First, just read it in
        for zz in range(chg.shape[2]):
            for yy in range(chg.shape[1]):
                chg[:, yy, zz] = np.fromfile(fobj, count=chg.shape[0],
                                             sep=' ')
        chg /= volume

    def read(self, filename='CHG'):
        """Read CHG or CHGCAR file.

        If CHG contains charge density from multiple steps all the
        steps are read and stored in the object. By default VASP
        writes out the charge density every 10 steps.

        chgdiff is the difference between the spin up charge density
        and the spin down charge density and is thus only read for a
        spin-polarized calculation.

        aug is the PAW augmentation charges found in CHGCAR. These are
        not parsed, they are just stored as a string so that they can
        be written again to a CHGCAR format file.

        """
        import ase.io.vasp as aiv
        f = open(filename)
        self.atoms = []
        self.chg = []
        self.chgdiff = []
        self.aug = ''
        self.augdiff = ''
        while True:
            try:
                atoms = aiv.read_vasp(f)
            except (IOError, ValueError, IndexError):
                # Probably an empty line, or we tried to read the
                # augmentation occupancies in CHGCAR
                break
            f.readline()
            ngr = f.readline().split()
            ng = (int(ngr[0]), int(ngr[1]), int(ngr[2]))
            chg = np.empty(ng)
            self._read_chg(f, chg, atoms.get_volume())
            self.chg.append(chg)
            self.atoms.append(atoms)
            # Check if the file has a spin-polarized charge density part, and
            # if so, read it in.
            fl = f.tell()
            # First check if the file has an augmentation charge part (CHGCAR
            # file.)
            line1 = f.readline()
            if line1 == '':
                break
            elif line1.find('augmentation') != -1:
                augs = [line1]
                while True:
                    line2 = f.readline()
                    if line2.split() == ngr:
                        self.aug = ''.join(augs)
                        augs = []
                        chgdiff = np.empty(ng)
                        self._read_chg(f, chgdiff, atoms.get_volume())
                        self.chgdiff.append(chgdiff)
                    elif line2 == '':
                        break
                    else:
                        augs.append(line2)
                if len(self.aug) == 0:
                    self.aug = ''.join(augs)
                    augs = []
                else:
                    self.augdiff = ''.join(augs)
                    augs = []
            elif line1.split() == ngr:
                chgdiff = np.empty(ng)
                self._read_chg(f, chgdiff, atoms.get_volume())
                self.chgdiff.append(chgdiff)
            else:
                f.seek(fl)
        f.close()

    def _write_chg(self, fobj, chg, volume, format='chg'):
        """Write charge density

        Utility function similar to _read_chg but for writing.

        """
        # Make a 1D copy of chg, must take transpose to get ordering right
        chgtmp = chg.T.ravel()
        # Multiply by volume
        chgtmp = chgtmp * volume
        # Must be a tuple to pass to string conversion
        chgtmp = tuple(chgtmp)
        # CHG format - 10 columns
        if format.lower() == 'chg':
            # Write all but the last row
            for ii in range((len(chgtmp) - 1) / 10):
                fobj.write(' %#11.5G %#11.5G %#11.5G %#11.5G %#11.5G\
 %#11.5G %#11.5G %#11.5G %#11.5G %#11.5G\n' % chgtmp[ii * 10:(ii + 1) * 10]
                           )
            # If the last row contains 10 values then write them without a
            # newline
            if len(chgtmp) % 10 == 0:
                fobj.write(' %#11.5G %#11.5G %#11.5G %#11.5G %#11.5G\
 %#11.5G %#11.5G %#11.5G %#11.5G %#11.5G' % chgtmp[len(chgtmp) - 10:len(chgtmp)])
            # Otherwise write fewer columns without a newline
            else:
                for ii in range(len(chgtmp) % 10):
                    fobj.write((' %#11.5G')
                               % chgtmp[len(chgtmp) - len(chgtmp) % 10 + ii])
        # Other formats - 5 columns
        else:
            # Write all but the last row
            for ii in range((len(chgtmp) - 1) / 5):
                fobj.write(' %17.10E %17.10E %17.10E %17.10E %17.10E\n'
                           % chgtmp[ii * 5:(ii + 1) * 5])
            # If the last row contains 5 values then write them without a
            # newline
            if len(chgtmp) % 5 == 0:
                fobj.write(' %17.10E %17.10E %17.10E %17.10E %17.10E'
                           % chgtmp[len(chgtmp) - 5:len(chgtmp)])
            # Otherwise write fewer columns without a newline
            else:
                for ii in range(len(chgtmp) % 5):
                    fobj.write((' %17.10E')
                               % chgtmp[len(chgtmp) - len(chgtmp) % 5 + ii])
        # Write a newline whatever format it is
        fobj.write('\n')
        # Clean up
        del chgtmp

    def write(self, filename='CHG', format=None):
        """Write VASP charge density in CHG format.

        filename: str
            Name of file to write to.
        format: str
            String specifying whether to write in CHGCAR or CHG
            format.

        """
        import ase.io.vasp as aiv
        if format is None:
            if filename.lower().find('chgcar') != -1:
                format = 'chgcar'
            elif filename.lower().find('chg') != -1:
                format = 'chg'
            elif len(self.chg) == 1:
                format = 'chgcar'
            else:
                format = 'chg'
        f = open(filename, 'w')
        for ii, chg in enumerate(self.chg):
            if format == 'chgcar' and ii != len(self.chg) - 1:
                continue  # Write only the last image for CHGCAR
            aiv.write_vasp(f, self.atoms[ii], direct=True, long_format=False)
            f.write('\n')
            for dim in chg.shape:
                f.write(' %4i' % dim)
            f.write('\n')
            vol = self.atoms[ii].get_volume()
            self._write_chg(f, chg, vol, format)
            if format == 'chgcar':
                f.write(self.aug)
            if self.is_spin_polarized():
                if format == 'chg':
                    f.write('\n')
                for dim in chg.shape:
                    f.write(' %4i' % dim)
                self._write_chg(f, self.chgdiff[ii], vol, format)
                if format == 'chgcar':
                    f.write('\n')
                    f.write(self.augdiff)
            if format == 'chg' and len(self.chg) > 1:
                f.write('\n')
        f.close()


class VaspDos(object):
    """Class for representing density-of-states produced by VASP

    The energies are in property self.energy

    Site-projected DOS is accesible via the self.site_dos method.

    Total and integrated DOS is accessible as numpy.ndarray's in the
    properties self.dos and self.integrated_dos. If the calculation is
    spin polarized, the arrays will be of shape (2, NDOS), else (1,
    NDOS).

    The self.efermi property contains the currently set Fermi
    level. Changing this value shifts the energies.

    """

    def __init__(self, doscar='DOSCAR', efermi=0.0):
        """Initialize"""
        self._efermi = 0.0
        self.read_doscar(doscar)
        self.efermi = efermi

        # we have determine the resort to correctly map ase atom index to the
        # POSCAR.
        self.sort = []
        self.resort = []
        if os.path.isfile('ase-sort.dat'):
            file = open('ase-sort.dat', 'r')
            lines = file.readlines()
            file.close()
            for line in lines:
                data = line.split()
                self.sort.append(int(data[0]))
                self.resort.append(int(data[1]))

    def _set_efermi(self, efermi):
        """Set the Fermi level."""
        ef = efermi - self._efermi
        self._efermi = efermi
        self._total_dos[0, :] = self._total_dos[0, :] - ef
        try:
            self._site_dos[:, 0, :] = self._site_dos[:, 0, :] - ef
        except IndexError:
            pass

    def _get_efermi(self):
        return self._efermi

    efermi = property(_get_efermi, _set_efermi, None, "Fermi energy.")

    def _get_energy(self):
        """Return the array with the energies."""
        return self._total_dos[0, :]
    energy = property(_get_energy, None, None, "Array of energies")

    def site_dos(self, atom, orbital):
        """Return an NDOSx1 array with dos for the chosen atom and orbital.

        atom: int
            Atom index
        orbital: int or str
            Which orbital to plot

        If the orbital is given as an integer:
        If spin-unpolarized calculation, no phase factors:
        s = 0, p = 1, d = 2
        Spin-polarized, no phase factors:
        s-up = 0, s-down = 1, p-up = 2, p-down = 3, d-up = 4, d-down = 5
        If phase factors have been calculated, orbitals are
        s, py, pz, px, dxy, dyz, dz2, dxz, dx2
        double in the above fashion if spin polarized.

        """
        # Correct atom index for resorting if we need to. This happens when the
        # ase-sort.dat file exists, and self.resort is not empty.
        if self.resort:
            atom = self.resort[atom]

        # Integer indexing for orbitals starts from 1 in the _site_dos array
        # since the 0th column contains the energies
        if isinstance(orbital, int):
            return self._site_dos[atom, orbital + 1, :]
        n = self._site_dos.shape[1]
        if n == 4:
            norb = {'s': 1, 'p': 2, 'd': 3}
        elif n == 7:
            norb = {'s+': 1, 's-up': 1, 's-': 2, 's-down': 2,
                    'p+': 3, 'p-up': 3, 'p-': 4, 'p-down': 4,
                    'd+': 5, 'd-up': 5, 'd-': 6, 'd-down': 6}
        elif n == 10:
            norb = {'s': 1, 'py': 2, 'pz': 3, 'px': 4,
                    'dxy': 5, 'dyz': 6, 'dz2': 7, 'dxz': 8,
                    'dx2': 9}
        elif n == 19:
            norb = {'s+': 1, 's-up': 1, 's-': 2, 's-down': 2,
                    'py+': 3, 'py-up': 3, 'py-': 4, 'py-down': 4,
                    'pz+': 5, 'pz-up': 5, 'pz-': 6, 'pz-down': 6,
                    'px+': 7, 'px-up': 7, 'px-': 8, 'px-down': 8,
                    'dxy+': 9, 'dxy-up': 9, 'dxy-': 10, 'dxy-down': 10,
                    'dyz+': 11, 'dyz-up': 11, 'dyz-': 12, 'dyz-down': 12,
                    'dz2+': 13, 'dz2-up': 13, 'dz2-': 14, 'dz2-down': 14,
                    'dxz+': 15, 'dxz-up': 15, 'dxz-': 16, 'dxz-down': 16,
                    'dx2+': 17, 'dx2-up': 17, 'dx2-': 18, 'dx2-down': 18}
        return self._site_dos[atom, norb[orbital.lower()], :]

    def _get_dos(self):
        if self._total_dos.shape[0] == 3:
            return self._total_dos[1, :]
        elif self._total_dos.shape[0] == 5:
            return self._total_dos[1:3, :]
    dos = property(_get_dos, None, None, 'Average DOS in cell')

    def _get_integrated_dos(self):
        if self._total_dos.shape[0] == 3:
            return self._total_dos[2, :]
        elif self._total_dos.shape[0] == 5:
            return self._total_dos[3:5, :]
    integrated_dos = property(_get_integrated_dos, None, None,
                              'Integrated average DOS in cell')

    def read_doscar(self, fname="DOSCAR"):
        """Read a VASP DOSCAR file"""
        f = open(fname)
        natoms = int(f.readline().split()[0])
        [f.readline() for nn in range(4)]  # Skip next 4 lines.
        # First we have a block with total and total integrated DOS
        ndos = int(f.readline().split()[2])
        dos = []
        for nd in range(ndos):
            dos.append(np.array([float(x) for x in f.readline().split()]))
        self._total_dos = np.array(dos).T
        # Next we have one block per atom, if INCAR contains the stuff
        # necessary for generating site-projected DOS
        dos = []
        for na in range(natoms):
            line = f.readline()
            if line == '':
                # No site-projected DOS
                break
            ndos = int(line.split()[2])
            line = f.readline().split()
            cdos = np.empty((ndos, len(line)))
            cdos[0] = np.array(line)
            for nd in range(1, ndos):
                line = f.readline().split()
                cdos[nd] = np.array([float(x) for x in line])
            dos.append(cdos.T)
        self._site_dos = np.array(dos)


class xdat2traj:
    def __init__(self, trajectory=None, atoms=None, poscar=None,
                 xdatcar=None, sort=None, calc=None):
        """
        trajectory is the name of the file to write the trajectory to
        poscar is the name of the poscar file to read. Default: POSCAR
        """
        if not poscar:
            self.poscar = 'POSCAR'
        else:
            self.poscar = poscar
        if not atoms:
            self.atoms = ase.io.read(self.poscar, format='vasp')
        else:
            self.atoms = atoms
        if not xdatcar:
            self.xdatcar = 'XDATCAR'
        else:
            self.xdatcar = xdatcar
        if not trajectory:
            self.trajectory = 'out.traj'
        else:
            self.trajectory = trajectory
        if not calc:
            self.calc = Vasp()
        else:
            self.calc = calc
        if not sort:
            if not hasattr(self.calc, 'sort'):
                self.calc.sort = list(range(len(self.atoms)))
        else:
            self.calc.sort = sort
        self.calc.resort = list(range(len(self.calc.sort)))
        for n in range(len(self.calc.resort)):
            self.calc.resort[self.calc.sort[n]] = n
        self.out = ase.io.trajectory.Trajectory(self.trajectory,
                                                mode='w')
        self.energies = self.calc.read_energy(all=True)[1]
        self.forces = self.calc.read_forces(self.atoms, all=True)

    def convert(self):
        lines = open(self.xdatcar).readlines()
        if len(lines[7].split()) == 0:
            del(lines[0:8])
        elif len(lines[5].split()) == 0:
            del(lines[0:6])
        elif len(lines[4].split()) == 0:
            del(lines[0:5])
        elif lines[7].split()[0] == 'Direct':
            del(lines[0:8])
        step = 0
        iatom = 0
        scaled_pos = []
        for line in lines:
            if iatom == len(self.atoms):
                if step == 0:
                    self.out.write_header(self.atoms[self.calc.resort])
                scaled_pos = np.array(scaled_pos)
                self.atoms.set_scaled_positions(scaled_pos)
                calc = SinglePointCalculator(self.atoms,
                                             energy=self.energies[step],
                                             forces=self.forces[step])
                self.atoms.set_calculator(calc)
                self.out.write(self.atoms)
                scaled_pos = []
                iatom = 0
                step += 1
            else:
                if not line.split()[0] == 'Direct':
                    iatom += 1
                    scaled_pos.append([float(line.split()[n])
                                       for n in range(3)])

        # Write also the last image
        # I'm sure there is also more clever fix...
        if step == 0:
            self.out.write_header(self.atoms[self.calc.resort])
        scaled_pos = np.array(scaled_pos)
        self.atoms.set_scaled_positions(scaled_pos)
        calc = SinglePointCalculator(self.atoms,
                                     energy=self.energies[step],
                                     forces=self.forces[step])
        self.atoms.set_calculator(calc)
        self.out.write(self.atoms)

        self.out.close()
