Analytic First-Order Derivatives of CASPT2 Combined with the Polarizable Continuum Model
Journal of Chemical Theory and Computation,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 16, 2025
The
complete
active
space
second-order
perturbation
theory
(CASPT2)
is
valuable
for
accurately
predicting
electronic
structures
and
transition
energies.
However,
optimizing
molecular
geometries
in
the
solution
phase
has
proven
challenging.
In
this
study,
we
develop
analytic
first-order
derivatives
of
CASPT2
using
an
implicit
solvation
model,
specifically
polarizable
continuum
within
open-source
package
OpenMolcas.
Analytic
gradients
nonadiabatic
coupling
vectors
are
computed
by
solving
a
modified
Z-vector
equation.
Comparisons
with
existing
theoretical
experimental
results
demonstrate
that
solvent
effects
can
be
qualitatively
captured
developed
method.
Language: Английский
Theory of frequency fluctuation of intramolecular vibration in solution phase: Application to C–N stretching mode of organic compounds
The Journal of Chemical Physics,
Journal Year:
2025,
Volume and Issue:
162(10)
Published: March 10, 2025
We
formulate
frequency
fluctuations
of
intramolecular
vibrations
a
solute
by
exploring
the
fluctuation
electrostatic
potential
solvents.
present
numerical
methodology
for
estimating
fluctuations;
is
based
on
reference
interaction
site
model
self-consistent
field
with
constrained
spatial
electron
density
distribution,
theoretical
solvation
fields
classical
statistic
mechanics.
By
applying
theory
to
C–N
stretching
several
nitrile
compounds,
our
estimated
scale
and
bandwidth
shift
changing
solvent
kinds
reproduced
experimental
data.
Furthermore,
we
regard
standard
deviation
as
multiple
random
variables
analyzing
fluctuations.
Our
results
reveal
that
dominant
almost
parallel
vibrational
axis.
In
addition,
become
spatially
nonuniform
solvents
form
stronger
hydrogen
bonds
solute.
The
development
confirms
nonuniformity
crucial
Language: Английский