Quantum Equation of Motion with Orbital Optimization for Computing Molecular Properties in Near-Term Quantum Computing
Journal of Chemical Theory and Computation,
Год журнала:
2024,
Номер
20(9), С. 3613 - 3625
Опубликована: Май 3, 2024
Determining
the
properties
of
molecules
and
materials
is
one
premier
applications
quantum
computing.
A
major
question
in
field
how
to
use
imperfect
near-term
computers
solve
problems
practical
value.
Inspired
by
recently
developed
variants
counterpart
equation-of-motion
(qEOM)
approach
orbital-optimized
variational
eigensolver
(oo-VQE),
we
present
a
algorithm
(oo-VQE-qEOM)
for
calculation
molecular
computing
expectation
values
on
computer.
We
perform
noise-free
simulations
BeH2
series
STO-3G/6-31G/6-31G*
basis
sets
H4
H2O
6-31G
using
an
active
space
four
electrons
spatial
orbitals
(8
qubits)
evaluate
excitation
energies,
electronic
absorption,
and,
twisted
H4,
circular
dichroism
spectra.
demonstrate
that
proposed
can
reproduce
results
conventional
classical
CASSCF
calculations
these
systems.
Язык: Английский
Understanding and mitigating noise in molecular quantum linear response for spectroscopic properties on quantum computers
Chemical Science,
Год журнала:
2025,
Номер
16(10), С. 4456 - 4468
Опубликована: Янв. 1, 2025
The
promise
of
quantum
computing
to
circumvent
the
exponential
scaling
chemistry
has
sparked
a
race
develop
algorithms
for
architecture.
However,
most
works
neglect
quantum-inherent
shot
noise,
let
alone
effect
current
noisy
devices.
Here,
we
present
comprehensive
study
linear
response
(qLR)
theory
obtaining
spectroscopic
properties
on
simulated
fault-tolerant
computers
and
present-day
near-term
hardware.
This
work
introduces
novel
metrics
analyze
predict
origins
noise
in
algorithm,
proposes
an
Ansatz-based
error
mitigation
technique,
reveals
significant
impact
Pauli
saving
reducing
measurement
costs
subspace
methods.
Our
hardware
results
using
up
cc-pVTZ
basis
set
serve
as
proof
principle
absorption
spectra
general
approach
with
accuracy
classical
multi-configurational
Importantly,
our
exemplify
that
substantial
improvements
rates
speed
are
necessary
lift
computational
from
concept
actual
field.
Язык: Английский
Subspace Methods for the Simulation of Molecular Response Properties on a Quantum Computer
Journal of Chemical Theory and Computation,
Год журнала:
2024,
Номер
20(9), С. 3729 - 3740
Опубликована: Май 1, 2024
We
explore
Davidson
methods
for
obtaining
excitation
energies
and
other
linear
response
properties
within
the
recently
developed
quantum
self-consistent
(q-sc-LR)
method.
Davidson-type
allow
only
a
few
selected
without
explicitly
constructing
electronic
Hessian
since
they
require
ability
to
perform
Hessian-vector
multiplications.
apply
method
calculate
of
hydrogen
chains
(up
H10)
analyze
aspects
statistical
noise
computing
on
simulators.
Additionally,
we
such
as
static
polarizabilities
H2,
LiH,
H2O,
OH–,
NH3,
show
that
unitary
coupled
cluster
outperforms
classical
projected
molecular
systems
with
strong
correlation.
Finally,
formulate
damped
(complex)
response,
application
nitrogen
K-edge
X-ray
absorption
ammonia,
C6
coefficients
NH3.
Язык: Английский
Quantum Computation of Conical Intersections on a Programmable Superconducting Quantum Processor
The Journal of Physical Chemistry Letters,
Год журнала:
2024,
Номер
15(28), С. 7244 - 7253
Опубликована: Июль 8, 2024
Conical
intersections
(CIs)
are
pivotal
in
many
photochemical
processes.
Traditional
quantum
chemistry
methods,
such
as
the
state-average
multiconfigurational
face
computational
hurdles
solving
electronic
Schrödinger
equation
within
active
space
on
classical
computers.
While
computing
offers
a
potential
solution,
its
feasibility
studying
CIs,
particularly
real
hardware,
remains
largely
unexplored.
Here,
we
present
first
successful
realization
of
hybrid
quantum-classical
complete
self-consistent
field
method
based
variational
eigensolver
(VQE-SA-CASSCF)
superconducting
processor.
This
approach
is
applied
to
investigate
CIs
two
prototypical
systems─ethylene
(C
Язык: Английский
Self-consistent Quantum Linear Response with a Polarizable Embedding Environment
The Journal of Physical Chemistry A,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 23, 2025
Quantum
computing
presents
a
promising
avenue
for
solving
complex
problems,
particularly
in
quantum
chemistry,
where
it
could
accelerate
the
computation
of
molecular
properties
and
excited
states.
This
work
focuses
on
excitation
energies
with
hybrid
quantum-classical
algorithms
near-term
devices,
combining
linear
response
(qLR)
method
polarizable
embedding
(PE)
environment.
We
employ
self-consistent
operator
manifold
(q-sc-LR)
top
unitary
coupled
cluster
(UCC)
wave
function
combination
Davidson
solver.
The
latter
removes
need
to
construct
entire
electronic
Hessian,
improving
computational
efficiency
when
going
toward
larger
molecules.
introduce
new
superposition-state-based
technique
compute
Hessian-vector
products
show
that
this
approach
is
more
resilient
noise
than
our
earlier
gradient-based
approach.
demonstrate
performance
PE-UCCSD
model
systems
such
as
butadiene
para-nitroaniline
water
find
delivers
comparable
accuracy
classical
PE-CCSD
methods
simple
closed-shell
systems.
also
explore
challenges
posed
by
hardware
propose
error
mitigation
techniques
maintain
accurate
results
noisy
computers.
Язык: Английский
Equation-of-motion internally contracted multireference unitary coupled-cluster theory
The Journal of Chemical Physics,
Год журнала:
2025,
Номер
162(15)
Опубликована: Апрель 16, 2025
The
accurate
computation
of
excited
states
remains
a
challenge
in
electronic
structure
theory,
especially
for
systems
with
ground
state
that
requires
multireference
treatment.
In
this
work,
we
introduce
novel
equation-of-motion
(EOM)
extension
the
internally
contracted
unitary
coupled-cluster
framework
(ic-MRUCC),
termed
EOM-ic-MRUCC.
EOM-ic-MRUCC
follows
transform-then-diagonalize
approach,
analogy
to
its
non-unitary
counterpart
[Datta
and
Nooijen,
J.
Chem.
Phys.
137,
204107
(2012)].
By
employing
projective
approach
optimize
state,
method
retains
additive
separability
proper
scaling
system
size.
We
show
excitation
energies
are
size-intensive
if
EOM
operator
satisfies
“killer”
conditions.
Furthermore,
propose
represent
changes
reference
upon
electron
via
projected
many-body
operators
span
active
orbitals
equations
formulated
way
invariant
respect
orbital
rotations.
test
truncated
single
double
excitations
by
computing
potential
energy
curves
several
BeH2
model
system,
HF
molecule,
water
undergoing
symmetric
dissociation.
Across
these
systems,
our
delivers
within
5
mEh
(∼0.14
eV)
from
full
configuration
interaction.
find
truncating
Baker–Campbell–Hausdorff
series
fourfold
commutators
contributes
negligible
errors
(on
order
10−5Eh
or
less),
offering
practical
route
highly
excited-state
calculations
reduced
computational
overhead.
Язык: Английский
Reduced Density Matrix Formulation of Quantum Linear Response
Journal of Chemical Theory and Computation,
Год журнала:
2024,
Номер
unknown
Опубликована: Авг. 6, 2024
The
prediction
of
spectral
properties
via
linear
response
(LR)
theory
is
an
important
tool
in
quantum
chemistry
for
understanding
photoinduced
processes
molecular
systems.
With
the
advances
computing,
we
recently
adapted
this
method
near-term
hardware
using
a
truncated
active
space
approximation
with
orbital
rotation,
named
(qLR).
In
effort
to
reduce
classic
cost
hybrid
approach,
here
derive
and
implement
reduced
density
matrix
(RDM)
driven
approach
qLR.
This
allows
calculation
moderately
sized
molecules
much
larger
basis
sets
than
so
far
possible.
We
report
qLR
results
benzene
Язык: Английский
Divergences in classical and quantum linear response and equation of motion formulations
The Journal of Chemical Physics,
Год журнала:
2024,
Номер
161(12)
Опубликована: Сен. 25, 2024
Calculating
molecular
properties
using
quantum
devices
can
be
performed
through
the
linear
response
(qLR)
or,
equivalently,
equation
of
motion
(qEOM)
formulations.
Different
parameterizations
qLR
and
qEOM
are
available,
namely
naïve,
projected,
self-consistent,
state-transfer.
In
naïve
projected
parameterizations,
metric
is
not
identity,
we
show
that
it
depends
on
redundant
orbital
rotations.
This
dependency
may
lead
to
divergences
in
excitation
energies
for
certain
choices
rotation
parameters
an
idealized
noiseless
setting.
Furthermore,
this
leads
a
significant
variance
when
calculations
include
statistical
noise
from
finite
sampling.
Язык: Английский
Determining the N-Representability of a Reduced Density Matrix via Unitary Evolution and Stochastic Sampling
Journal of Chemical Theory and Computation,
Год журнала:
2024,
Номер
20(22), С. 9968 - 9976
Опубликована: Ноя. 14, 2024
The
N-representability
problem
consists
in
determining
whether,
for
a
given
p-body
matrix,
there
exists
at
least
one
N-body
density
matrix
from
which
the
can
be
obtained
by
contraction,
that
is,
if
is
reduced
(p-RDM).
knowledge
of
all
necessary
and
sufficient
conditions
to
N-representable
allows
constrained
minimization
many-body
Hamiltonian
expectation
value
with
respect
and,
thus,
determination
its
exact
ground
state.
However,
number
constraints
complete
grows
exponentially
system
size,
hence,
procedure
quickly
becomes
intractable
practical
applications.
This
work
introduces
hybrid
quantum-stochastic
algorithm
effectively
replace
conditions.
applying
an
initial
sequence
unitary
evolution
operators
constructed
stochastic
process
successively
approaches
state
on
subsystem,
represented
p-RDM,
target
potentially
p-RDM.
generators
follow
well-known
adaptive
derivative-assembled
pseudo-Trotter
method
(ADAPT),
while
component
implemented
using
simulated
annealing
process.
resulting
independent
any
underlying
Hamiltonian,
it
used
decide
whether
N-representable,
establishing
criterion
determine
quality
correcting
it.
We
apply
proposed
ADAPT
alleged
matrices
quantum
chemistry
electronic
Bardeen–Cooper–Schrieffer
model
constant
pairing,
Heisenberg
XXZ
spin
model.
In
cases,
behaves
as
expected
1-RDMs
2-RDMs,
evolving
toward
different
targets.
Язык: Английский