Coupled-Cluster Study of Spectroscopic Constants of the Alkali Metal Diatomics: Ground and the Singlet Excited States of Na2, NaLi, NaK, and NaRb

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Title:Coupled-Cluster Study of Spectroscopic Constants of the Alkali Metal Diatomics: Ground and the Singlet Excited States of Na2, NaLi, NaK, and NaRb
Creators:
Neogrády, Pavel
Szalay, Péter G.
Kraemer, Wolfgang P.
Urban, Miroslav
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 70, 7, pp. 951-978
Uncontrolled Keywords:<i>Ab initio</i> calculations, Complete active space, Na<sub>2</sub>, NaLi, NaK, and NaRb, Potential energy curves, Singlet excited states, Multireference coupled-cluster calculations, Incomplete active space, TD-CCSD

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 X<sup>1</sup>Σ<sup>+</sup><sub>u</sub> and the two singlet mono-excited states, A<sup>1</sup>Σ<sup>+</sup><sub>u</sub> and B<sup>1</sup>Π<sub>u</sub> of Na<sub>2</sub> as well as for the ground X<sup>1</sup>Σ<sup>+</sup> and the singlet excited A<sup>1</sup>Σ<sup>+</sup> and B<sup>1</sup>Π 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. <p>

Title:Coupled-Cluster Study of Spectroscopic Constants of the Alkali Metal Diatomics: Ground and the Singlet Excited States of Na2, NaLi, NaK, and NaRb
Creators:
Neogrády, Pavel
Szalay, Péter G.
Kraemer, Wolfgang P.
Urban, Miroslav
Uncontrolled Keywords:<i>Ab initio</i> calculations, Complete active space, Na<sub>2</sub>, NaLi, NaK, and NaRb, Potential energy curves, Singlet excited states, Multireference coupled-cluster calculations, Incomplete active space, TD-CCSD
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:70
Number:7
Page Range:pp. 951-978
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20050951UNSPECIFIED
ID Code:2401
Item Type:Article
Deposited On:06 Feb 2009 17:18
Last Modified:06 Feb 2009 16:18

Citation

Neogrády, Pavel; Szalay, Péter G.; Kraemer, Wolfgang P.; Urban, Miroslav (2005) Coupled-Cluster Study of Spectroscopic Constants of the Alkali Metal Diatomics: Ground and the Singlet Excited States of Na2, NaLi, NaK, and NaRb. Collection of Czechoslovak Chemical Communications, 70 (7). pp. 951-978. ISSN 0010-0765

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