# Copyright 2022 The ipie 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
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# Authors: Fionn Malone <fionn.malone@gmail.com>
# Joonho Lee
#
import numpy
from ipie.utils.backend import arraylib as xp
from ipie.utils.misc import is_cupy
# TODO: Rename this
[docs]def kinetic_real(phi, system, bt2, H1diag=False):
r"""Propagate by the kinetic term by direct matrix multiplication.
For use with the continuus algorithm and free propagation.
todo : this is the same a propagating by an arbitrary matrix, remove.
Parameters
----------
walker : :class:`pie.walker.Walker`
Walker object to be updated. on output we have acted on
:math:`|\phi_i\rangle` by :math:`B_{T/2}` and updated the weight
appropriately. updates inplace.
state : :class:`pie.state.State`
Simulation state.
"""
nup = system.nup
# Assuming that our walker is in UHF form.
if H1diag:
phi[:, :nup] = xp.einsum("ii,ij->ij", bt2[0], phi[:, :nup])
phi[:, nup:] = xp.einsum("ii,ij->ij", bt2[1], phi[:, nup:])
else:
phi[:, :nup] = bt2[0].dot(phi[:, :nup])
phi[:, nup:] = bt2[1].dot(phi[:, nup:])
[docs]def kinetic_spin_real_batch(phi, bt2, H1diag=False):
r"""Propagate by the kinetic term by direct matrix multiplication. Only one spin component. Assuming phi is a batch.
For use with the continuus algorithm and free propagation.
todo : this is the same a propagating by an arbitrary matrix, remove.
Parameters
----------
walker : :class:`pie.walker.Walker`
Walker object to be updated. on output we have acted on
:math:`|\phi_i\rangle` by :math:`B_{T/2}` and updated the weight
appropriately. updates inplace.
state : :class:`pie.state.State`
Simulation state.
"""
# Assuming that our walker is in UHF form.
if H1diag:
phi[:, :] = xp.einsum("ii,wij->ij", bt2, phi)
else:
if is_cupy(bt2):
phi = xp.einsum("ik,wkj->wij", bt2, phi, optimize=True)
else:
# Loop is O(10x) times faster on CPU for FeP benchmark
for iw in range(phi.shape[0]):
phi[iw] = xp.dot(bt2, phi[iw])
return phi