Coupled-cluster study of spectroscopic constants of the alkali metal diatomics: Ground and the singlet excited states of Na2, NaLi, NaK, and NaRb

Pavel Neogrády, Péter G. Szalay, Wolfgang P. Kraemer, Miroslav Urban

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

A newly implemented two-determinant coupled-cluster method including single and double excitation operators (TD-CCSD) is applied to calculations of spectroscopic constants of alkali metal diatomics. The equilibrium bond length, harmonic vibrational frequency, anharmonicity, the dissociation energy and excitation energies are derived from the potential curves calculated for the ground state X1Σ8+ and the two singlet mono-excited states, A1Σu+ and B 1Πu of Na2 as well as for the ground X 1Σ+ and the singlet excited A1Σ + and B1Π states of the heteronuclear NaLi, NaK, and NaRb molecules. Spectroscopic constants and excitation energies agree reasonably well with experiment. Our results demonstrate that the relatively simple CCSD method for the excited states represented by two-reference determinants is a viable technique. The computer time needed for an excited singlet state is practically identical to the time which a standard single-determinant-based CCSD calculation takes.

Original languageEnglish
Pages (from-to)951-978
Number of pages28
JournalCollection of Czechoslovak Chemical Communications
Volume70
Issue number7
DOIs
Publication statusPublished - Jul 1 2005

Keywords

  • Ab initio calculations
  • Complete active space
  • Incomplete active space
  • Multireference coupled-cluster calculations
  • Na , NaLi, NaK, and NaRb
  • Potential energy curves
  • Singlet excited states
  • TD-CCSD

ASJC Scopus subject areas

  • Chemistry(all)

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