Are ab initio quantum chemistry methods able to predict vibrational states up to the dissociation limit for multi-electron molecules close to spectroscopic accuracy?

P. Szalay, Filip Holka, Julien Fremont, Michael Rey, Kirk A. Peterson, Vladimir G. Tyuterev

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The aim of the study was to explore the limits of ab initio methods towards the description of excited vibrational levels up to the dissociation limit for molecules having more than two electrons. To this end a high level ab initio potential energy function was constructed for the four-electron LiH molecule in order to accurately predict a complete set of bound vibrational levels corresponding to the electronic ground state. It was composed from: (a) an ab initio non-relativistic potential obtained at the MR-CISD level including size-extensivity corrections and quintuple-sextuple ζ extrapolation of the basis, (b) MVD relativistic corrections obtained at icMR-CISD/cc-pwCV5Z level, and (c) DBOC obtained at the MR-CISD/cc-pwCVTZ level. Finally, the importance of non-adiabatic effects was also tested by using atomic masses in the vibrational kinetic energy operator. The calculated vibrational levels were compared with those obtained from experimental data [J. A. Coxon and C. S. Dickinson, J. Chem. Phys., 2004, 121, 9378]. Our best estimate of the potential curve results in vibrational energies with a RMS deviation of only ∼1 cm-1 for the entire set of all empirically determined vibrational levels known so far. These results represent a drastic improvement over previous theoretical predictions of vibrational levels of 7LiH up to dissociation, D0, which was predicted to be 19594 cm-1.

Original languageEnglish
Pages (from-to)3654-3659
Number of pages6
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number9
DOIs
Publication statusPublished - Mar 7 2011

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Quantum chemistry
quantum chemistry
vibrational states
Potential energy functions
dissociation
Molecules
Electrons
Extrapolation
Kinetic energy
Ground state
molecules
electrons
atomic weights
extrapolation
kinetic energy
potential energy
deviation
operators
ground state

ASJC Scopus subject areas

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

Cite this

Are ab initio quantum chemistry methods able to predict vibrational states up to the dissociation limit for multi-electron molecules close to spectroscopic accuracy? / Szalay, P.; Holka, Filip; Fremont, Julien; Rey, Michael; Peterson, Kirk A.; Tyuterev, Vladimir G.

In: Physical Chemistry Chemical Physics, Vol. 13, No. 9, 07.03.2011, p. 3654-3659.

Research output: Contribution to journalArticle

Szalay, P. ; Holka, Filip ; Fremont, Julien ; Rey, Michael ; Peterson, Kirk A. ; Tyuterev, Vladimir G. / Are ab initio quantum chemistry methods able to predict vibrational states up to the dissociation limit for multi-electron molecules close to spectroscopic accuracy?. In: Physical Chemistry Chemical Physics. 2011 ; Vol. 13, No. 9. pp. 3654-3659.
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