A Higher Level Ab Initio Quantum-Mechanical Study of the Quadrupole Moment Tensor Components of Carbon Dioxide

Abstract

The quadrupolarity of carbon dioxide has been studied with higher level ab initio methods. Carbon dioxide exhibits {- + -} quadrupolarity in all directions and an explanation is provided of the origin of the sign of the diagonal elements Qii. The quadrupole moment tensor has been computed using restricted Hartree-Fock theory, second-order Møller-Plesset perturbation theory and quadratic configuration interaction theory. A variety of basis sets have been employed up to basis sets of the type [5s, 4p, 2d, 1f] (23s, 8p, 2d, 1f). The quadrupole moment tensor component Q∥ of carbon dioxide falls in the range between -18.5 and -20.5 Debye Å. The quadrupole moment tensor components Q⊥ of carbon dioxide are smaller, ranging from -14.5 to -15 Debye Å, and they are less sensitive to the choice of the theoretical model. The correlated methods consistently predict an increase of Q∥ while they predict a more modest reduction of Q⊥. It is for the opposing electron correlation effects on Q∥ and Q⊥ that the average values of the diagonal elements, 〈Qii〉, are essentially independent of the method and exhibit only a small variation depending on the basis set. On the other hand, the anisotropy of the quadrupolarity, the quadrupole moment Θ, is affected most by the opposing electron correlation effects on Q∥ and Q⊥. The accurate reproduction of the measured quadrupolarity Θ = -4.3 Debye Å requires a theoretical model that employs both a good method and a good basis set. The results suggest that the use of second-order Møller-Plesset perturbation theory in conjunction with well-polarized triple-ζ basis sets provides a cost-effective and quite accurate method for the estimation of correlation effects on quadrupole moments.

Department(s)

Chemistry

Sponsor(s)

University of Missouri Research Council

Comments

This research was supported by the MU Research Council

Keywords and Phrases

Carbon Dioxide; Anisotropy; Catalysis; Deamination; Dehydration; Dipole; Hydrogen Bond; Hydrolysis; Molecular Interaction; Nucleotide Metabolism; Quantum Mechanics; Reaction Analysis; Ab Initio Calculations; Atomic Charges; Electrostatic Bonding; Quadrupole Moment Tensor Components

International Standard Serial Number (ISSN)

0022-2860

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2000 Elsevier, All rights reserved.

Publication Date

01 Dec 2000

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