#!/usr/bin/env python
# Copyright 2014-2019 The PySCF Developers. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Authors: Shiv Upadhyay <shivnupadhyay@gmail.com>
#
'''
Valence Virtual Orbitals
ref. 10.1021/acs.jctc.7b00493
'''
import numpy
import scipy.linalg
from pyscf.lo import iao
from pyscf.lo import orth
from pyscf.lo import ibo
from pyscf import __config__
[docs]
def vvo(mol, orbocc, orbvirt, iaos=None, s=None, verbose=None):
'''Valence Virtual Orbitals ref. 10.1021/acs.jctc.7b00493
Valence virtual orbitals can be formed from the singular value
decomposition of the overlap between the canonical molecular orbitals
and an accurate underlying atomic basis set. This implementation uses
the intrinsic atomic orbital as this underlying set. VVOs can also be
formed from the null space of the overlap of the canonical molecular
orbitals and the underlying atomic basis sets (IAOs). This is not
implemented here.
Args:
mol : the molecule or cell object
orbocc : occupied molecular orbital coefficients
orbvirt : virtual molecular orbital coefficients
Kwargs:
iaos : 2D array
the array of IAOs
s : 2D array
the overlap array in the ao basis
Returns:
VVOs in the basis defined in mol object.
'''
if s is None:
if getattr(mol, 'pbc_intor', None): # whether mol object is a cell
if isinstance(orbocc, numpy.ndarray) and orbocc.ndim == 2:
s = mol.pbc_intor('int1e_ovlp', hermi=1)
else:
raise NotImplementedError('k-points crystal orbitals')
else:
s = mol.intor_symmetric('int1e_ovlp')
if iaos is None:
iaos = iao.iao(mol, orbocc)
nvvo = iaos.shape[1] - orbocc.shape[1]
# Symmetrically orthogonalization of the IAO orbitals as Knizia's
# implementation. The IAO returned by iao.iao function is not orthogonal.
iaos = orth.vec_lowdin(iaos, s)
#S = reduce(np.dot, (orbvirt.T, s, iaos))
S = numpy.einsum('ji,jk,kl->il', orbvirt.conj(), s, iaos, optimize=True)
U, sigma, Vh = scipy.linalg.svd(S)
U = U[:, 0:nvvo]
vvo = numpy.einsum('ik,ji->jk', U, orbvirt, optimize=True)
return vvo
[docs]
def livvo(mol, orbocc, orbvirt, locmethod='IBO', iaos=None, s=None,
exponent=4, grad_tol=1e-8, max_iter=200, verbose=None):
'''Localized Intrinsic Valence Virtual Orbitals ref. 10.1021/acs.jctc.7b00493
Localized Intrinsic valence virtual orbitals are formed when the valence
virtual orbitals are localized using an IBO-type of localization. Here
the VVOs are created in the IAO basis then the IBO localization functions
are called to localize the VVOs.
Args:
mol : the molecule or cell object
orbocc : occupied molecular orbital coefficients
orbvirt : virtual molecular orbital coefficients
Kwargs:
locmethod : string
the localization method 'PM' for Pipek Mezey localization or 'IBO'
for the IBO localization
iaos : 2D array
the array of IAOs
s : 2D array
the overlap array in the ao basis
Returns:
LIVVOs in the basis defined in mol object.
'''
if s is None:
if getattr(mol, 'pbc_intor', None): # whether mol object is a cell
if isinstance(orbocc, numpy.ndarray) and orbocc.ndim == 2:
s = mol.pbc_intor('int1e_ovlp', hermi=1)
else:
raise NotImplementedError('k-points crystal orbitals')
else:
s = mol.intor_symmetric('int1e_ovlp')
if iaos is None:
iaos = iao.iao(mol, orbocc)
vvos = vvo(mol, orbocc, orbvirt, iaos=iaos, s=s)
locmethod = locmethod.strip().upper()
if locmethod == 'PM':
EXPONENT = getattr(__config__, 'lo_ibo_PipekMezey_exponent', exponent)
livvos = ibo.PipekMezey(mol, vvos, iaos, s, exponent=EXPONENT)
del (EXPONENT)
else:
livvos = ibo.ibo_loc(mol, vvos, iaos, s, exponent=exponent,
grad_tol=grad_tol, max_iter=max_iter,
verbose=verbose)
return livvos
