#!/usr/bin/env python
# Copyright 2014-2021 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>
#
import numpy
from pyscf import lib
from pyscf.cc import ccsd_rdm
def _gamma1_intermediates(mycc, t1, t2, l1, l2, eris=None, for_grad=False):
doo, dov, dvo, dvv = ccsd_rdm._gamma1_intermediates(mycc, t1, t2, l1, l2)
if eris is None: eris = mycc.ao2mo()
nocc, nvir = t1.shape
eris_ovvv = numpy.asarray(eris.get_ovvv())
eris_ovoo = numpy.asarray(eris.ovoo)
eris_ovov = numpy.asarray(eris.ovov)
mo_e = eris.mo_energy
eia = lib.direct_sum('i-a->ia', mo_e[:nocc], mo_e[nocc:])
d3 = lib.direct_sum('ia,jb,kc->ijkabc', eia, eia, eia)
w = (numpy.einsum('iafb,kjcf->ijkabc', eris_ovvv.conj(), t2) -
numpy.einsum('iajm,mkbc->ijkabc', eris_ovoo.conj(), t2)) / d3
v = (numpy.einsum('iajb,kc->ijkabc', eris_ovov.conj(), t1) +
numpy.einsum('ck,ijab->ijkabc', eris.fock[nocc:,:nocc], t2)) / d3
w = p6(w)
v = p6(v)
wv = w + v * .5
rw = r6(w)
goo = numpy.einsum('iklabc,jklabc->ij', wv.conj(), rw)
gvv = numpy.einsum('ijkacd,ijkbcd->ab', wv, rw.conj())
if not for_grad:
# t3 amplitudes in CCSD(T) is computed non-iteratively. The
# off-diagonal blocks of fock matrix does not contribute to CCSD(T)
# energy. To make Tr(H,D) consistent to the CCSD(T) total energy, the
# density matrix off-diagonal parts are excluded.
doo[numpy.diag_indices(nocc)] -= goo.diagonal() * .5
dvv[numpy.diag_indices(nvir)] += gvv.diagonal() * .5
else:
# The off-diagonal blocks of fock matrix have small contributions to
# analytical nuclear gradients.
doo -= goo * .5
dvv += gvv * .5
dvo += numpy.einsum('ijab,ijkabc->ck', t2.conj(), rw) * .5
return doo, dov, dvo, dvv
def _gamma2_intermediates(mycc, t1, t2, l1, l2, eris=None,
compress_vvvv=False):
'''intermediates tensors for gamma2 are sorted in Chemist's notation
'''
dovov, dvvvv, doooo, doovv, dovvo, dvvov, dovvv, dooov = \
ccsd_rdm._gamma2_intermediates(mycc, t1, t2, l1, l2)
if eris is None: eris = mycc.ao2mo()
nocc, nvir = t1.shape
eris_ovvv = numpy.asarray(eris.get_ovvv())
eris_ovoo = numpy.asarray(eris.ovoo)
eris_ovov = numpy.asarray(eris.ovov)
mo_e = eris.mo_energy
eia = lib.direct_sum('i-a->ia', mo_e[:nocc], mo_e[nocc:])
d3 = lib.direct_sum('ia,jb,kc->ijkabc', eia, eia, eia)
w = (numpy.einsum('iafb,kjcf->ijkabc', eris_ovvv.conj(), t2) -
numpy.einsum('iajm,mkbc->ijkabc', eris_ovoo.conj(), t2)) / d3
v = (numpy.einsum('iajb,kc->ijkabc', eris_ovov.conj(), t1) +
numpy.einsum('ck,ijab->ijkabc', eris.fock[nocc:,:nocc], t2)) / d3
w = p6(w)
v = p6(v)
rw = r6(w)
rwv = r6(w * 2 + v * .5)
dovov += numpy.einsum('kc,ijkabc->iajb', t1, rw.conj()) * .5
dooov -= numpy.einsum('mkbc,ijkabc->jmia', t2, rwv.conj())
# Note "dovvv +=" also changes the value of dvvov
dovvv += numpy.einsum('kjcf,ijkabc->iafb', t2, rwv.conj())
dvvov = dovvv.transpose(2,3,0,1)
if compress_vvvv:
nvir = mycc.nmo - mycc.nocc
idx = numpy.tril_indices(nvir)
vidx = idx[0] * nvir + idx[1]
dvvvv = dvvvv + dvvvv.transpose(1,0,2,3)
dvvvv = dvvvv + dvvvv.transpose(0,1,3,2)
dvvvv = lib.take_2d(dvvvv.reshape(nvir**2,nvir**2), vidx, vidx)
dvvvv *= .25
return dovov, dvvvv, doooo, doovv, dovvo, dvvov, dovvv, dooov
def _gamma2_outcore(mycc, t1, t2, l1, l2, eris, h5fobj, compress_vvvv=False):
return _gamma2_intermediates(mycc, t1, t2, l1, l2, eris, compress_vvvv)
[docs]
def make_rdm1(mycc, t1, t2, l1, l2, eris=None, ao_repr=False):
d1 = _gamma1_intermediates(mycc, t1, t2, l1, l2, eris)
return ccsd_rdm._make_rdm1(mycc, d1, True, ao_repr=ao_repr)
# rdm2 in Chemist's notation
[docs]
def make_rdm2(mycc, t1, t2, l1, l2, eris=None):
d1 = _gamma1_intermediates(mycc, t1, t2, l1, l2, eris)
d2 = _gamma2_intermediates(mycc, t1, t2, l1, l2, eris)
return ccsd_rdm._make_rdm2(mycc, d1, d2, True, True)
[docs]
def p6(t):
t1 = t + t.transpose(0,2,1,3,5,4)
return t1 + t1.transpose(1,0,2,4,3,5) + t1.transpose(1,2,0,4,5,3)
[docs]
def r6(w):
return (4 * w + w.transpose(0,1,2,4,5,3) + w.transpose(0,1,2,5,3,4)
- 2 * w.transpose(0,1,2,5,4,3) - 2 * w.transpose(0,1,2,3,5,4)
- 2 * w.transpose(0,1,2,4,3,5))
