#!/usr/bin/env python
# Copyright 2014-2020 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.
#
# Author: Qiming Sun <osirpt.sun@gmail.com>
# Elvira R. Sayfutyarova
#
'''
Automated construction of molecular active spaces from atomic valence orbitals.
Ref. arXiv:1701.07862 [physics.chem-ph]
'''
from functools import reduce
import numpy
import scipy.linalg
from pyscf import lib
from pyscf import gto
from pyscf import scf
from pyscf.lib import logger
from pyscf import __config__
THRESHOLD = getattr(__config__, 'mcscf_avas_threshold', 0.2)
MINAO = getattr(__config__, 'mcscf_avas_minao', 'minao')
WITH_IAO = getattr(__config__, 'mcscf_avas_with_iao', False)
OPENSHELL_OPTION = getattr(__config__, 'mcscf_avas_openshell_option', 2)
CANONICALIZE = getattr(__config__, 'mcscf_avas_canonicalize', True)
[docs]
def kernel(mf, aolabels, threshold=THRESHOLD, minao=MINAO, with_iao=WITH_IAO,
openshell_option=OPENSHELL_OPTION, canonicalize=CANONICALIZE,
ncore=0, verbose=None):
'''AVAS method to construct mcscf active space.
Ref. arXiv:1701.07862 [physics.chem-ph]
Args:
mf : an :class:`SCF` object
aolabels : string or a list of strings
AO labels for AO active space
Kwargs:
threshold : float
Tructing threshold of the AO-projector above which AOs are kept in
the active space.
minao : str
A reference AOs for AVAS.
with_iao : bool
Whether to use IAO localization to construct the reference active AOs.
openshell_option : int
How to handle singly-occupied orbitals in the active space. The
singly-occupied orbitals are projected as part of alpha orbitals
if openshell_option=2, or completely kept in active space if
openshell_option=3. See Section III.E option 2 or 3 of the
reference paper for more details.
canonicalize : bool
Orbitals defined in AVAS method are local orbitals. Symmetrizing
the core, active and virtual space.
ncore : integer
Number of core orbitals to be excluded from the AVAS method.
Returns:
active-space-size, #-active-electrons, orbital-initial-guess-for-CASCI/CASSCF
Examples:
>>> from pyscf import gto, scf, mcscf
>>> from pyscf.mcscf import avas
>>> mol = gto.M(atom='Cr 0 0 0; Cr 0 0 1.6', basis='ccpvtz')
>>> mf = scf.RHF(mol).run()
>>> ncas, nelecas, mo = avas.avas(mf, ['Cr 3d', 'Cr 4s'])
>>> mc = mcscf.CASSCF(mf, ncas, nelecas).run(mo)
'''
avas_obj = AVAS(mf, aolabels, threshold, minao, with_iao,
openshell_option, canonicalize, ncore, verbose)
return avas_obj.kernel()
def _kernel(avas_obj):
mf = avas_obj._scf
mol = mf.mol
log = logger.new_logger(avas_obj)
log.info('\n** AVAS **')
assert avas_obj.openshell_option != 1
if isinstance(mf, scf.uhf.UHF):
log.note('UHF/UKS object is found. AVAS takes alpha orbitals only')
mo_coeff = mf.mo_coeff[0]
mo_occ = mf.mo_occ[0]
mo_energy = mf.mo_energy[0]
else:
mo_coeff = mf.mo_coeff
mo_occ = mf.mo_occ
mo_energy = mf.mo_energy
ncore = avas_obj.ncore
nocc = numpy.count_nonzero(mo_occ != 0)
ovlp = mol.intor_symmetric('int1e_ovlp')
log.info(' Total number of HF MOs is equal to %d' ,mo_coeff.shape[1])
log.info(' Number of occupied HF MOs is equal to %d', nocc)
mol = mf.mol
pmol = mol.copy()
pmol.atom = mol._atom
pmol.unit = 'B'
pmol.symmetry = False
pmol.basis = avas_obj.minao
pmol.build(False, False)
baslst = pmol.search_ao_label(avas_obj.aolabels)
log.info('reference AO indices for %s %s:\n %s',
avas_obj.minao, avas_obj.aolabels, baslst)
if avas_obj.with_iao:
from pyscf.lo import iao
c = iao.iao(mol, mo_coeff[:,ncore:nocc], avas_obj.minao)[:,baslst]
s2 = reduce(numpy.dot, (c.T, ovlp, c))
s21 = reduce(numpy.dot, (c.T, ovlp, mo_coeff[:, ncore:]))
else:
s2 = pmol.intor_symmetric('int1e_ovlp')[baslst][:,baslst]
s21 = gto.intor_cross('int1e_ovlp', pmol, mol)[baslst]
s21 = numpy.dot(s21, mo_coeff[:, ncore:])
sa = s21.T.dot(scipy.linalg.solve(s2, s21, assume_a='pos'))
threshold = avas_obj.threshold
if avas_obj.openshell_option == 2:
wocc, u = numpy.linalg.eigh(sa[:(nocc-ncore), :(nocc-ncore)])
log.info('Option 2: threshold %s', threshold)
ncas_occ = (wocc > threshold).sum()
nelecas = (mol.nelectron - ncore * 2) - (wocc < threshold).sum() * 2
mocore = mo_coeff[:,ncore:nocc].dot(u[:,wocc<threshold])
mocas = mo_coeff[:,ncore:nocc].dot(u[:,wocc>=threshold])
wvir, u = numpy.linalg.eigh(sa[(nocc-ncore):,(nocc-ncore):])
ncas_vir = (wvir > threshold).sum()
mocas = numpy.hstack((mocas,
mo_coeff[:,nocc:].dot(u[:,wvir>=threshold])))
movir = mo_coeff[:,nocc:].dot(u[:,wvir<threshold])
ncas = mocas.shape[1]
occ_weights = numpy.hstack([wocc[wocc<threshold], wocc[wocc>=threshold]])
vir_weights = numpy.hstack([wvir[wvir>=threshold], wvir[wvir<threshold]])
elif avas_obj.openshell_option == 3:
docc = nocc - mol.spin
wocc, u = numpy.linalg.eigh(sa[:(docc-ncore),:(docc-ncore)])
log.info('Option 3: threshold %s, num open shell %d', threshold, mol.spin)
ncas_occ = (wocc > threshold).sum()
nelecas = (mol.nelectron - ncore * 2) - (wocc < threshold).sum() * 2
mocore = mo_coeff[:,ncore:docc].dot(u[:,wocc<threshold])
mocas = mo_coeff[:,ncore:docc].dot(u[:,wocc>=threshold])
wvir, u = numpy.linalg.eigh(sa[(nocc-ncore):,(nocc-ncore):])
ncas_vir = (wvir > threshold).sum()
mocas = numpy.hstack((mocas,
mo_coeff[:,docc:nocc],
mo_coeff[:,nocc:].dot(u[:,wvir>=threshold])))
movir = mo_coeff[:,nocc:].dot(u[:,wvir<threshold])
ncas = mocas.shape[1]
occ_weights = numpy.hstack([wocc[wocc<threshold], numpy.ones(nocc-docc),
wocc[wocc>=threshold]])
vir_weights = numpy.hstack([wvir[wvir>=threshold], wvir[wvir<threshold]])
else:
raise RuntimeError(f'Unknown option openshell_option {avas_obj.openshell_option}')
log.debug('projected occ eig %s', occ_weights)
log.debug('projected vir eig %s', vir_weights)
log.info('Active from occupied = %d , eig %s', ncas_occ, occ_weights[occ_weights>=threshold])
log.info('Inactive from occupied = %d', mocore.shape[1])
log.info('Active from unoccupied = %d , eig %s', ncas_vir, vir_weights[vir_weights>=threshold])
log.info('Inactive from unoccupied = %d', movir.shape[1])
log.info('Dimensions of active %d', ncas)
nalpha = (nelecas + mol.spin) // 2
nbeta = nelecas - nalpha
log.info('# of alpha electrons %d', nalpha)
log.info('# of beta electrons %d', nbeta)
mofreeze = mo_coeff[:,:ncore]
if avas_obj.canonicalize:
from pyscf.mcscf import dmet_cas
def trans(c):
if c.shape[1] == 0:
return c
else:
csc = reduce(numpy.dot, (c.T, ovlp, mo_coeff))
fock = numpy.dot(csc*mo_energy, csc.T)
e, u = scipy.linalg.eigh(fock)
return dmet_cas.symmetrize(mol, e, numpy.dot(c, u), ovlp, log)
if ncore > 0:
mofreeze = trans(mofreeze)
mocore = trans(mocore)
mocas = trans(mocas)
movir = trans(movir)
mo = numpy.hstack((mofreeze, mocore, mocas, movir))
return ncas, nelecas, mo, occ_weights, vir_weights
avas = kernel
[docs]
@lib.with_doc(kernel.__doc__)
class AVAS(lib.StreamObject):
def __init__(self, mf, aolabels, threshold=THRESHOLD, minao=MINAO,
with_iao=WITH_IAO, openshell_option=OPENSHELL_OPTION,
canonicalize=CANONICALIZE, ncore=0, verbose=None):
self._scf = mf
self.aolabels = aolabels
self.threshold = threshold
self.minao = minao
self.with_iao = with_iao
self.openshell_option = openshell_option
self.canonicalize = canonicalize
self.ncore = ncore
self.stdout = mf.stdout
self.verbose = verbose or mf.verbose
##################################################
# don't modify the following attributes, they are not input options
self.ncas = None
self.nelecas = None
# Orbitals of entire space, including cores, actives, externals
self.mo_coeff = None
# occ_weights and vir_weights to filter active and inactive orbitals
self.occ_weights = None
self.vir_weights = None
[docs]
def dump_flags(self, verbose=None):
log = logger.new_logger(self, verbose)
log.info('')
log.info('******** AVAS flags ********')
log.info('aolabels = %s', self.aolabels)
log.info('ncore = %s', self.ncore)
log.info('minao = %s', self.minao)
log.info('threshold = %s', self.threshold)
log.info('with_iao = %s', self.with_iao)
log.info('openshell_option = %s', self.openshell_option)
log.info('canonicalize = %s', self.canonicalize)
return self
[docs]
def kernel(self):
self.dump_flags()
self.ncas, self.nelecas, self.mo_coeff, \
self.occ_weights, self.vir_weights = _kernel(self)
return self.ncas, self.nelecas, self.mo_coeff
