Source code for psi4.driver.qmmm

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"""Module with classes to integrate MM charges into
a QM calculation.

"""
from __future__ import absolute_import

from psi4.driver import *


class Diffuse(object):

    def __init__(self, molecule, basisname, ribasisname):

        self.molecule = molecule
        self.basisname = basisname
        self.ribasisname = ribasisname
        self.basis = None
        self.ribasis = None
        self.da = None
        self.Da = None
        self.wfn = None

    def __str__(self):

        s = '    => Diffuse <=\n\n'
        s = s + '    ' + str(self.molecule) + '\n'
        s = s + '    ' + self.basisname + '\n'
        s = s + '    ' + self.ribasisname + '\n'
        s = s + '\n'

        return s

    def fitScf(self):
        """Function to run scf and fit a system of diffuse charges to
        resulting density.

        """
        basisChanged = core.has_option_changed("BASIS")
        ribasisChanged = core.has_option_changed("DF_BASIS_SCF")
        scftypeChanged = core.has_option_changed("SCF_TYPE")

        basis = core.get_option("BASIS")
        ribasis = core.get_option("DF_BASIS_SCF")
        scftype = core.get_global_option("SCF_TYPE")

        core.print_out("    => Diffuse SCF (Determines Da) <=\n\n")

        core.set_global_option("BASIS", self.basisname)
        core.set_global_option("DF_BASIS_SCF", self.ribasisname)
        core.set_global_option("SCF_TYPE", "DF")
        E, ref = energy('scf', return_wfn=True, molecule=self.molecule)
        self.wfn = ref
        core.print_out("\n")

        self.fitGeneral()

        core.clean()

        core.set_global_option("BASIS", basis)
        core.set_global_option("DF_BASIS_SCF", ribasis)
        core.set_global_option("SCF_TYPE", scftype)

        if not basisChanged:
            core.revoke_option_changed("BASIS")
        if not ribasisChanged:
            core.revoke_option_changed("DF_BASIS_SCF")
        if not scftypeChanged:
            core.revoke_option_changed("SCF_TYPE")

    def fitGeneral(self):
        """Function to perform a general fit of diffuse charges
        to wavefunction density.

        """
        core.print_out("    => Diffuse Charge Fitting (Determines da) <=\n\n")
        self.Da = self.wfn.Da()
        self.basis = self.wfn.basisset()
        parser = core.Gaussian94BasisSetParser()
        self.ribasis = core.BasisSet.construct(parser, self.molecule, "DF_BASIS_SCF")

        fitter = core.DFChargeFitter()
        fitter.setPrimary(self.basis)
        fitter.setAuxiliary(self.ribasis)
        fitter.setD(self.Da)
        self.da = fitter.fit()
        self.da.scale(2.0)

    def populateExtern(self, extern):
        # Electronic Part
        extern.addBasis(self.ribasis, self.da)
        # Nuclear Part
        for A in range(0, self.molecule.natom()):
            extern.addCharge(self.molecule.Z(A), self.molecule.x(A), self.molecule.y(A), self.molecule.z(A))


[docs]class QMMM(object): def __init__(self): self.charges = [] self.diffuses = [] self.extern = core.ExternalPotential()
[docs] def addDiffuse(self, diffuse): """Function to add a diffuse charge field *diffuse*.""" self.diffuses.append(diffuse)
[docs] def addChargeBohr(self, Q, x, y, z): """Function to add a point charge of magnitude *Q* at position (*x*, *y*, *z*) Bohr. """ self.charges.append([Q, x, y, z])
[docs] def addChargeAngstrom(self, Q, x, y, z): """Function to add a point charge of magnitude *Q* at position (*x*, *y*, *z*) Angstroms. """ self.charges.append([Q, x / constants.bohr2angstroms, y / constants.bohr2angstroms, z / constants.bohr2angstroms])
def __str__(self): s = ' ==> QMMM <==\n\n' s = s + ' => Charges (a.u.) <=\n\n' s = s + ' %11s %11s %11s %11s\n' % ('Z', 'x', 'y', 'z') for k in range(0, len(self.charges)): s = s + ' %11.7f %11.3E %11.3E %11.3E\n' % (self.charges[k][0], self.charges[k][1], self.charges[k][2], self.charges[k][3]) s = s + '\n' s = s + ' => Diffuses <=\n\n' for k in range(0, len(self.diffuses)): s = s + str(self.diffuses[k]) return s
[docs] def populateExtern(self): """Function to define a charge field external to the molecule through point and diffuse charges. """ # Charges for charge in self.charges: self.extern.addCharge(charge[0], charge[1], charge[2], charge[3]) # Diffuses for diffuse in self.diffuses: diffuse.populateExtern(self.extern)