Chimie Théorique » QMX

"""This module defines an ASE interface to DftbPlus

http://http://www.dftb-plus.info//

http://www.dftb.org/

-Markus Kaukonen markus.kaukonen@iki.fi

"""

import numpy as np

import os, string

#from ase.data import chemical_symbols

from ase.units import Hartree, Bohr

class Dftb:

    """Class for doing DFTB+ calculations.

    """

    def __init__(self, label='dftb', write_dftb=False,

                 charge=0.0, include_dispersion=False,

                 do_spin_polarized=False, 

                 unpaired_electrons=0.0,

                 fermi_temperature=0.0, scc=False):

        """Construct DFTB-calculator object.

        For example:

        calc = Dftb(label='dftb',write_dftb=True,include_dispersion=True )

        Parameters

        ==========

        label: str

            Prefix to use for filenames (label.txt, ...).

            Default is 'dftb'.

        write_dftb: boolean

            True: a minimal input file (name of which is always 'dftb_in.hsd')

            is written based on values given here.

            False: input file for dftb+ is not written. User must have

            generated file 'dftb_in.hsd' in the working directory.

            Use write_dftb=False to use your own 'dftb_in.hsd'-file.

        charge: float

            Total charge of the system.

        include_dispersion: boolean

            True: Default dispersion parameters are written in the 

            file 'dftb_in.hsd' (requires that also write_dftb_input_file==True)

            False: dispersion parameters are not written here.

        do_spin_polarized: boolean

            True: Spin polarized calculation

            (requires that also write_dftb_input_file==True)

            False: Spin unpolarized calculation

        unpaired_electrons: float

            Number of spin unpaired electrons in the system.

            Relevant only if do_spin_polarized==True

        fermi_temperature: float

            Fermi temperature for electrons.

        scc: boolean

            True: Do charge self consistent dftb+

            False: No SCC, charges on atoms are not iterated

        Input file for DFTB+ file is 'dftb_in.hsd'. Keywords in it are

        written here or read from an existing file. The atom positions

        in file 'dftb_in.hsd' are updated during ASE geometry

        optimization.

        """

        if not(write_dftb):

            if os.path.isfile('dftb_in.hsd'):

                f = open('dftb_in.hsd')

            else:

                print 'Input file for DFTB+ dftb_in.hsd is missing'

                raise RuntimeError, \

                    'Provide it or set write_dftb=True '

            #lines = f.readlines()

            f.close()

        self.label = label

        self.write_dftb = write_dftb

        self.charge = charge

        self.include_dispersion = include_dispersion

        self.do_spin_polarized = do_spin_polarized

        self.unpaired_electrons = unpaired_electrons

        #if (do_spin_polarized):

        #    print 'Sorry, generation of file "dftb_in.hsd" with spin '

        #    print 'polarization is not inplemented for DFTB+'

        #    print 'Set write_dftb=False and'

        #    raise RuntimeError, \

        #        'Generate file "dftb_in.hsd by hand"'

        self.etotal = 0.0

        self.cell = None

        self.fermi_temperature = fermi_temperature

        self.scc = scc 

        self.converged = False

        #dftb has no stress

        self.stress = np.empty((3, 3))

    def update(self, atoms):

        """Energy and forces are calculated when atoms have moved

        by calling self.calculate

        """

        if (not self.converged or

            len(self.typenumber) != len(atoms)):

            self.initialize(atoms)

            self.calculate(atoms)

        elif ((self.positions != atoms.get_positions()).any() or

              (self.pbc != atoms.get_pbc()).any() or

              (self.cell != atoms.get_cell()).any()):

            self.calculate(atoms)

    def initialize(self, atoms):

        #from ase.io.dftb import read_dftb

        atomtypes = atoms.get_chemical_symbols()

        self.allspecies = []

        self.typenumber = []

        self.max_angular_momentum = []

        for species in (atomtypes):

            if species not in self.allspecies:

                self.allspecies.append(species)

        for species in (atomtypes):

            myindex = 1 + self.allspecies.index(species)

            self.typenumber.append(myindex)

        for i in self.allspecies:

            if i == 'H':

                self.max_angular_momentum.append('s')

            elif i in ['C','N','O']:

                self.max_angular_momentum.append('p')

            elif i in ['Si','S','Fe','Ni']:

                self.max_angular_momentum.append('d')

            else:

                print 'anglular momentum is not imlemented in ASE-DFTB+'

                print 'for species '+i

                raise RuntimeError('Use option write_dftb=False')

        self.converged = False

        #write DFTB input file if desired 

        self.positions = atoms.get_positions().copy()

        if self.write_dftb:

            self.write_dftb_input_file(atoms)

    def get_potential_energy(self, atoms):

        self.update(atoms)

        return self.etotal

    def get_forces(self, atoms):

        self.update(atoms)

        return self.forces.copy()

    def get_stress(self, atoms):

        self.update(atoms)

        return self.stress.copy()

    def calculate(self, atoms):

        """Total DFTB energy is calculated (to file 'energy'

        also forces are calculated (to file 'gradient')

        """

        self.positions = atoms.get_positions().copy()

        self.cell = atoms.get_cell().copy()

        self.pbc = atoms.get_pbc().copy()

        if self.write_dftb:

            self.write_dftb_input_file(atoms)

        else:

            #write current coordinates to file 'dftb_in.hsd' for DFTB+

            self.change_atom_positions_dftb(atoms)

        #DFTB energy&forces calculation

        if (os.environ.has_key('DFTB_COMMAND') and

            (os.environ.has_key('DFTB_PREFIX'))):

            dftb = os.environ['DFTB_COMMAND']

            exitcode = os.system(dftb+ '> dftb.output' )

        elif not(os.environ.has_key('DFTB_COMMAND')):

            raise RuntimeError('Please set DFTB_COMMAND environment variable')

        elif not(os.environ.has_key('DFTB_PREFIX')):

            print 'Path for DFTB+ slater koster files is missing'    

            raise RuntimeError('Please set DFTB_PREFIX environment variable')

        else:

            pass

        if exitcode != 0:

            raise RuntimeError('Dftb exited with exit code: %d.  ' % exitcode)

        self.read_energy()

        #DFTB atomic forces calculation, to be read in file detailed.out

        #os.system(self.dftb_program_forces +'> output.forces.dummy')

        self.read_forces(atoms)

        self.converged = True

    def read_energy(self):

        """Read Energy from DFTB energy file."""

        text = open('dftb.output', 'r').read().lower()

        lines = iter(text.split('\n'))

        # Energy:

        for line in lines:

            if 'total energy' in line:

                energy_tmp = float(line.split()[2])

                #print 'energy_tmp', energy_tmp

        self.etotal = energy_tmp * Hartree

    def read_forces(self, atoms):

        """Read Forces from DFTB+ detailed.out output file"""

        myfile = open('detailed.out','r')

        line = myfile.readline()

        line = myfile.readline()

        tmpforces = np.array([[0, 0, 0]])

        while line:

            if 'Total Forces' in line:

                for i, dummy in enumerate(atoms):

                    line = myfile.readline()

                    line2 = string.replace(line, 'D', 'E')

                    tmp = np.array\

                        ([[float(f) for f in line2.split()[0:3]]])

                    tmpforces = np.concatenate((tmpforces, tmp))  

            line = myfile.readline()

        self.forces = (np.delete(tmpforces, np.s_[0:1], axis=0))*Hartree/Bohr

        #print 'forces', self.forces

    def read(self):

        """Dummy stress for dftb"""

        self.stress = np.empty((3, 3))

    def write_dftb_input_file(self, atoms):

        """Write input parameters to DFTB+ input file 'dftb_in.hsd'."""

        import sys

        fh = open('dftb_in.hsd', 'w')

        # geometry

        fh.write('Geometry = {\n')

        fh.write('TypeNames = {')

        for i in self.allspecies:

            fh.write(' "'+i+'"')

        fh.write(' }\n')

        fh.write('TypesAndCoordinates [Angstrom] = {\n')

        self.positions = atoms.get_positions().copy()

        for i, pos in zip(self.typenumber, self.positions):

            fh.write('%6d ' % (i))

            fh.write('%20.14f %20.14f %20.14f' %  tuple(pos))

            fh.write('\n')

        fh.write(' }\n')

        #is it periodic and when is write also lattice vectors

        periodic = atoms.get_pbc().any()

        if periodic:

            fh.write('Periodic = Yes\n')

        else:

            fh.write('Periodic = No\n')

        if periodic:

            cell = atoms.get_cell().copy()

            fh.write('LatticeVectors [Angstrom] = {\n')

            for v in cell:

                fh.write('%20.14f %20.14f %20.14f \n' %  tuple(v))

            fh.write('  }\n')

        #end of geometry session

        fh.write('}\n')

        #zero step CG relaxation to get forces and energies

        # these are dummies because ASE takes care of these things

        fh.write('\n') 

        fh.write('Driver = ConjugateGradient {\n')

        fh.write('MovedAtoms = Range { 1 -1 }\n')

        fh.write('  MaxForceComponent = 1.0e-4\n')

        fh.write('  MaxSteps = 0\n')

        fh.write('  OutputPrefix = '+self.label+ '\n')

        fh.write('}\n')

        #Hamiltonian

        fh.write('\n') 

        fh.write('Hamiltonian = DFTB { # DFTB Hamiltonian\n')

        if (self.scc):

            fh.write('  SCC = Yes')

            fh.write(' # Use self consistent charges\n')               

            fh.write('  SCCTolerance = 1.0e-5')

            fh.write(' # Tolerance for charge consistence\n')            

            fh.write('  MaxSCCIterations = 1000')

            fh.write(' # Nr. of maximal SCC iterations\n')          

            fh.write('  Mixer = Broyden {') 

            fh.write(' # Broyden mixer for charge mixing\n')          

            fh.write('    MixingParameter = 0.2')  

            fh.write(' # Mixing parameter\n')

            fh.write('  }\n')

        else:

            fh.write('  SCC = No # NO self consistent charges\n')

        fh.write('  SlaterKosterFiles = Type2FileNames {')

        fh.write(' # File names from two atom type names\n')

        sk_prefix = os.environ['DFTB_PREFIX']

        fh.write('    Prefix = "'+sk_prefix+'"')

        fh.write(' # Path as prefix\n')

        fh.write('    Separator = "-"')

        fh.write(' # Dash between type names\n')

        fh.write('    Suffix = ".skf"')

        fh.write(' # Suffix after second type name\n')

        fh.write('  }\n')

        fh.write('  MaxAngularMomentum = {')

        fh.write(' # Maximal l-value of the various species\n')

        for i, j in zip(self.allspecies, self.max_angular_momentum):

            fh.write('   '+i+' = "'+j+'"\n')

        fh.write('  }\n')

        fh.write('  Charge = ')

        fh.write('%10.6f' % (self.charge))

        fh.write(' # System neutral\n')

        if self.do_spin_polarized:

            fh.write('  SpinPolarisation = Colinear {\n') 

            fh.write('  UnpairedElectrons = '+str(self.unpaired_electrons)+'\n')

            fh.write('  } \n')

            fh.write('  SpinConstants = {\n') 

            for i in self.allspecies:

                if i == 'H':

                    fh.write('   H={\n') 

                    fh.write('    # Wss\n') 

                    fh.write('    -0.072\n') 

                    fh.write('    }\n')

                elif i == 'C': 

                    fh.write('   C={\n') 

                    fh.write('    # Wss Wsp Wps Wpp\n') 

                    fh.write('    -0.031 -0.025 -0.025 -0.023\n') 

                    fh.write('    }\n') 

                elif i == 'N': 

                    fh.write('   N={\n') 

                    fh.write('    # Wss Wsp Wps Wpp\n')

                    fh.write('    -0.033 -0.027 -0.027 -0.026\n') 

                    fh.write('     }\n') 

                elif i == 'O':

                    fh.write('   O={\n') 

                    fh.write('    # Wss Wsp Wps Wpp\n') 

                    fh.write('    -0.035 -0.030 -0.030 -0.028\n') 

                    fh.write('     }\n') 

                elif (i == 'Si' or i == 'SI'):

                    fh.write('   Si={\n') 

                    fh.write('    # Wss Wsp Wsd Wps Wpp Wpd Wds Wdp Wdd\n')

                    fh.write('    -0.020 -0.015 0.000 -0.015 -0.014 0.000 0.002 0.002 -0.032\n')

                    fh.write('    }\n')

                elif (i == 'S'):

                    fh.write('   S={\n') 

                    fh.write('    # Wss Wsp Wsd Wps Wpp Wpd Wds Wdp Wdd\n') 

                    fh.write('    -0.021 -0.017 0.000 -0.017 -0.016 0.000 0.000 0.000 -0.080\n')

                    fh.write('    }\n')

                elif (i == 'Fe' or i == 'FE'):

                    fh.write('   Fe={\n') 

                    fh.write('    # Wss Wsp Wsd Wps Wpp Wpd Wds Wdp Wdd\n') 

                    fh.write('    -0.016 -0.012 -0.003 -0.012 -0.029 -0.001 -0.003 -0.001 -0.015\n')

                    fh.write('    }\n')

                elif (i == 'Ni' or i == 'NI'):

                    fh.write('   Ni={\n') 

                    fh.write('    # Wss Wsp Wsd Wps Wpp Wpd Wds Wdp Wdd\n') 

                    fh.write('    -0.016 -0.012 -0.003 -0.012 -0.022 -0.001 -0.003 -0.001 -0.018\n')

                    fh.write('    }\n')

                else:

                    print 'Missing spin polarisation parameters for species'+i

                    raise RuntimeError, \

                        'Run spin unpolarised calculation'

                fh.write('   }\n') 

        else:

            fh.write('  SpinPolarisation = {}')

            fh.write(' # No spin polarisation\n')

        fh.write('  Filling = Fermi {\n')

        fh.write('    Temperature [Kelvin] = ')

        fh.write('%10.6f\n' % (self.fermi_temperature))

        fh.write('  }\n')

        if periodic:

            fh.write('# gamma only\n')

            fh.write('KPointsAndWeights = { \n')

            fh.write('  0.000000    0.000000    0.000000       1.000000 \n')

            fh.write('}\n')

        #Dispersion parameters

        if (self.include_dispersion):

            fh.write('Dispersion = SlaterKirkwood {\n')

            fh.write(' PolarRadiusCharge = HybridDependentPol {\n')

            fh.write('\n')

            fh.write('  C={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.8\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('      1.382 1.382 1.382 1.064 1.064 1.064 3.8 3.8 3.8 3.8 3.8 3.8 2.5\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write('\n')

            fh.write('  N={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.8\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('      1.030 1.030 1.090 1.090 1.090 1.090 3.8 3.8 3.8 3.8 3.8 3.8 2.82\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write('\n')

            fh.write('  O={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.8\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('    # All polarisabilities and radii set the same\n')

            fh.write('      0.560 0.560 0.000 0.000 0.000 0.000 3.8 3.8 3.8 3.8 3.8 3.8 3.15\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write('\n')

            fh.write('  H={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.4\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('    # Different polarisabilities depending on the hybridisation\n')

            fh.write('      0.386 0.396 0.000 0.000 0.000 0.000 3.5 3.5 3.5 3.5 3.5 3.5 0.8\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write('\n')

            fh.write('  P={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.9\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('    # Different polarisabilities depending on the hybridisation\n')

            fh.write('      1.600 1.600 1.600 1.600 1.600 1.600 4.7 4.7 4.7 4.7 4.7 4.7 4.50\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write('\n')

            fh.write('  S={\n')

            fh.write('    CovalentRadius [Angstrom] = 0.9\n')

            fh.write('    HybridPolarisations [Angstrom^3,Angstrom,] = {\n')

            fh.write('    # Different polarisabilities depending on the hybridisation\n')

            fh.write('      3.000 3.000 3.000 3.000 3.000 3.000 4.7 4.7 4.7 4.7 4.7 4.7 4.80\n')

            fh.write('    }\n')

            fh.write('  }\n')

            fh.write(' }\n')        

            fh.write('}\n') 

        fh.write('}\n') 

        fh.write('Options = {}\n')

        fh.write('ParserOptions = {\n')

        fh.write('  ParserVersion = 3\n')

        fh.write('}\n')

        fh.close()

    def change_atom_positions_dftb(self, atoms):

        """Write coordinates in DFTB+ input file dftb_in.hsd

        """

        filename = 'dftb_in.hsd'

        if isinstance(filename, str):

            myfile = open(filename)

        lines = myfile.readlines()

        if type(filename) == str:

            myfile.close()

        if isinstance(filename, str):

            myfile = open(filename, 'w')

        else: # Assume it's a 'file-like object'

            myfile = filename

        coord = atoms.get_positions()

        start_writing_coords = False

        stop_writing_coords = False

        i = 0

        for line in lines:

            if ('TypesAndCoordinates' in line):

                start_writing_coords = True

            if (start_writing_coords and not(stop_writing_coords)):

                if ('}' in line):

                    stop_writing_coords = True

            if (start_writing_coords and not(stop_writing_coords)and 

                not ('TypesAndCoordinates' in line)):

                atom_type_index = line.split()[0]

                myfile.write('%6s  %20.14f  %20.14f  %20.14f\n'

                        % (atom_type_index,coord[i][0],coord[i][1],coord[i][2]))

                i = i + 1

            else:

                myfile.write(line)