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# -*- coding: utf-8 -*-
#
# Copyright (c) 2018, the cclib development team
#
# This file is part of cclib (http://cclib.github.io) and is distributed under
# the terms of the BSD 3-Clause License.
"""Löwdin population analysis."""
import random
import numpy
from cclib.method.population import Population
class LPA(Population):
"""The Löwdin population analysis"""
def __init__(self, *args):
# Call the __init__ method of the superclass.
super(LPA, self).__init__(logname="LPA", *args)
def __str__(self):
"""Return a string representation of the object."""
return "LPA of %s" % (self.data)
def __repr__(self):
"""Return a representation of the object."""
return 'LPA("%s")' % (self.data)
def calculate(self, indices=None, x=0.5, fupdate=0.05):
"""Perform a calculation of Löwdin population analysis.
Inputs:
indices - list of lists containing atomic orbital indices of fragments
x - overlap matrix exponent in wavefunxtion projection (x=0.5 for Lowdin)
"""
unrestricted = (len(self.data.mocoeffs) == 2)
nbasis = self.data.nbasis
# Determine number of steps, and whether process involves beta orbitals.
self.logger.info("Creating attribute aoresults: [array[2]]")
alpha = len(self.data.mocoeffs[0])
self.aoresults = [ numpy.zeros([alpha, nbasis], "d") ]
nstep = alpha
if unrestricted:
beta = len(self.data.mocoeffs[1])
self.aoresults.append(numpy.zeros([beta, nbasis], "d"))
nstep += beta
# intialize progress if available
if self.progress:
self.progress.initialize(nstep)
if hasattr(self.data, "aooverlaps"):
S = self.data.aooverlaps
elif hasattr(self.data, "fooverlaps"):
S = self.data.fooverlaps
# Get eigenvalues and matrix of eigenvectors for transformation decomposition (U).
# Find roots of diagonal elements, and transform backwards using eigevectors.
# We need two matrices here, one for S^x, another for S^(1-x).
# We don't need to invert U, since S is symmetrical.
eigenvalues, U = numpy.linalg.eig(S)
UI = U.transpose()
Sdiagroot1 = numpy.identity(len(S))*numpy.power(eigenvalues, x)
Sdiagroot2 = numpy.identity(len(S))*numpy.power(eigenvalues, 1-x)
Sroot1 = numpy.dot(U, numpy.dot(Sdiagroot1, UI))
Sroot2 = numpy.dot(U, numpy.dot(Sdiagroot2, UI))
step = 0
for spin in range(len(self.data.mocoeffs)):
for i in range(len(self.data.mocoeffs[spin])):
if self.progress and random.random() < fupdate:
self.progress.update(step, "Lowdin Population Analysis")
ci = self.data.mocoeffs[spin][i]
temp1 = numpy.dot(ci, Sroot1)
temp2 = numpy.dot(ci, Sroot2)
self.aoresults[spin][i] = numpy.multiply(temp1, temp2).astype("d")
step += 1
if self.progress:
self.progress.update(nstep, "Done")
retval = super(LPA, self).partition(indices)
if not retval:
self.logger.error("Error in partitioning results")
return False
# Create array for charges.
self.logger.info("Creating fragcharges: array[1]")
size = len(self.fragresults[0][0])
self.fragcharges = numpy.zeros([size], "d")
alpha = numpy.zeros([size], "d")
if unrestricted:
beta = numpy.zeros([size], "d")
for spin in range(len(self.fragresults)):
for i in range(self.data.homos[spin] + 1):
temp = numpy.reshape(self.fragresults[spin][i], (size,))
self.fragcharges = numpy.add(self.fragcharges, temp)
if spin == 0:
alpha = numpy.add(alpha, temp)
elif spin == 1:
beta = numpy.add(beta, temp)
if not unrestricted:
self.fragcharges = numpy.multiply(self.fragcharges, 2)
else:
self.logger.info("Creating fragspins: array[1]")
self.fragspins = numpy.subtract(alpha, beta)
return True
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