Assigning quantum labels to variationally computed rotational-vibrational eigenstates of polyatomic molecules

E. Mat́yus, Csaba Fábri, Tamás Szidarovszky, G. Czakó, Wesley D. Allen, A. Császár

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

A procedure is investigated for assigning physically transparent, approximate vibrational and rotational quantum labels to variationally computed eigenstates. Pure vibrational wave functions are analyzed by means of normal-mode decomposition (NMD) tables constructed from overlap integrals with respect to separable harmonic oscillator basis functions. Complementary rotational labels J Ka Kc are determined from rigid-rotor decomposition (RRD) tables formed by projecting rotational-vibrational wave functions (J≠0) onto products of symmetrized rigid-rotor basis functions and previously computed (J=0) vibrational eigenstates. Variational results for H2 O, HNCO, trans-HCOD, NCCO, and H2 CCO are presented to demonstrate the NMD and RRD schemes. The NMD analysis highlights several resonances at low energies that cause strong mixing and cloud the assignment of fundamental vibrations, even in such simple molecules. As the vibrational energy increases, the NMD scheme documents and quantifies the breakdown of the normal-mode model. The RRD procedure proves effective in providing unambiguous rotational assignments for the chosen test molecules up to moderate J values.

Original languageEnglish
Article number034113
JournalThe Journal of Chemical Physics
Volume133
Issue number3
DOIs
Publication statusPublished - Jul 21 2010

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polyatomic molecules
Labels
eigenvectors
Rigid rotors
rigid rotors
Decomposition
decomposition
Molecules
Wave functions
wave functions
harmonic oscillators
molecules
breakdown
vibration
energy
causes
products

ASJC Scopus subject areas

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

Cite this

Assigning quantum labels to variationally computed rotational-vibrational eigenstates of polyatomic molecules. / Mat́yus, E.; Fábri, Csaba; Szidarovszky, Tamás; Czakó, G.; Allen, Wesley D.; Császár, A.

In: The Journal of Chemical Physics, Vol. 133, No. 3, 034113, 21.07.2010.

Research output: Contribution to journalArticle

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