A second-order multi-reference perturbation method for molecular vibrations

Wataru Mizukami, David P. Tew

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We present a general multi-reference framework for treating strong correlation in vibrational structure theory, which we denote the vibrational active space self-consistent field (VASSCF) approach. Active configurations can be selected according to excitation level or the degrees of freedom involved, or both. We introduce a novel state-specific second-order multi-configurational perturbation correction that accounts for the remaining weak correlation between the vibrational modes. The resulting VASPT2 method is capable of accurately and efficiently treating strong correlation in the form of large anharmonic couplings, at the same time as correctly resolving resonances between states. These methods have been implemented in our new dynamics package DYNAMOL, which can currently treat up to four-body Hamiltonian coupling terms. We present a pilot application of the VASPT2 method to the trans isomer of formic acid. We have constructed a new analytic potential that reproduces frozen core CCSD(T)(F12*)/cc-pVDZ-F12 energies to within 0.25% RMSD over the energy range 0-15 000 cm-1. The computed VASPT2 fundamental transition energies are accurate to within 9 cm-1 RMSD from experimental values, which is close to the accuracy one can expect from a CCSD(T) potential energy surface.

Original languageEnglish
Article number194108
JournalJournal of Chemical Physics
Volume139
Issue number19
DOIs
Publication statusPublished - Nov 21 2013
Externally publishedYes

Fingerprint

formic acid
Molecular vibrations
Hamiltonians
Potential energy surfaces
Isomers
perturbation
vibration
self consistent fields
energy
vibration mode
isomers
degrees of freedom
potential energy
configurations
excitation

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

A second-order multi-reference perturbation method for molecular vibrations. / Mizukami, Wataru; Tew, David P.

In: Journal of Chemical Physics, Vol. 139, No. 19, 194108, 21.11.2013.

Research output: Contribution to journalArticle

@article{cf8e1004710f4ba2922a00f815cb17c5,
title = "A second-order multi-reference perturbation method for molecular vibrations",
abstract = "We present a general multi-reference framework for treating strong correlation in vibrational structure theory, which we denote the vibrational active space self-consistent field (VASSCF) approach. Active configurations can be selected according to excitation level or the degrees of freedom involved, or both. We introduce a novel state-specific second-order multi-configurational perturbation correction that accounts for the remaining weak correlation between the vibrational modes. The resulting VASPT2 method is capable of accurately and efficiently treating strong correlation in the form of large anharmonic couplings, at the same time as correctly resolving resonances between states. These methods have been implemented in our new dynamics package DYNAMOL, which can currently treat up to four-body Hamiltonian coupling terms. We present a pilot application of the VASPT2 method to the trans isomer of formic acid. We have constructed a new analytic potential that reproduces frozen core CCSD(T)(F12*)/cc-pVDZ-F12 energies to within 0.25{\%} RMSD over the energy range 0-15 000 cm-1. The computed VASPT2 fundamental transition energies are accurate to within 9 cm-1 RMSD from experimental values, which is close to the accuracy one can expect from a CCSD(T) potential energy surface.",
author = "Wataru Mizukami and Tew, {David P.}",
year = "2013",
month = "11",
day = "21",
doi = "10.1063/1.4830100",
language = "English",
volume = "139",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "19",

}

TY - JOUR

T1 - A second-order multi-reference perturbation method for molecular vibrations

AU - Mizukami, Wataru

AU - Tew, David P.

PY - 2013/11/21

Y1 - 2013/11/21

N2 - We present a general multi-reference framework for treating strong correlation in vibrational structure theory, which we denote the vibrational active space self-consistent field (VASSCF) approach. Active configurations can be selected according to excitation level or the degrees of freedom involved, or both. We introduce a novel state-specific second-order multi-configurational perturbation correction that accounts for the remaining weak correlation between the vibrational modes. The resulting VASPT2 method is capable of accurately and efficiently treating strong correlation in the form of large anharmonic couplings, at the same time as correctly resolving resonances between states. These methods have been implemented in our new dynamics package DYNAMOL, which can currently treat up to four-body Hamiltonian coupling terms. We present a pilot application of the VASPT2 method to the trans isomer of formic acid. We have constructed a new analytic potential that reproduces frozen core CCSD(T)(F12*)/cc-pVDZ-F12 energies to within 0.25% RMSD over the energy range 0-15 000 cm-1. The computed VASPT2 fundamental transition energies are accurate to within 9 cm-1 RMSD from experimental values, which is close to the accuracy one can expect from a CCSD(T) potential energy surface.

AB - We present a general multi-reference framework for treating strong correlation in vibrational structure theory, which we denote the vibrational active space self-consistent field (VASSCF) approach. Active configurations can be selected according to excitation level or the degrees of freedom involved, or both. We introduce a novel state-specific second-order multi-configurational perturbation correction that accounts for the remaining weak correlation between the vibrational modes. The resulting VASPT2 method is capable of accurately and efficiently treating strong correlation in the form of large anharmonic couplings, at the same time as correctly resolving resonances between states. These methods have been implemented in our new dynamics package DYNAMOL, which can currently treat up to four-body Hamiltonian coupling terms. We present a pilot application of the VASPT2 method to the trans isomer of formic acid. We have constructed a new analytic potential that reproduces frozen core CCSD(T)(F12*)/cc-pVDZ-F12 energies to within 0.25% RMSD over the energy range 0-15 000 cm-1. The computed VASPT2 fundamental transition energies are accurate to within 9 cm-1 RMSD from experimental values, which is close to the accuracy one can expect from a CCSD(T) potential energy surface.

UR - http://www.scopus.com/inward/record.url?scp=84903367723&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84903367723&partnerID=8YFLogxK

U2 - 10.1063/1.4830100

DO - 10.1063/1.4830100

M3 - Article

C2 - 24320317

AN - SCOPUS:84903367723

VL - 139

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 19

M1 - 194108

ER -