Alkali and alkaline earth metal compounds: core-valence basis sets and importance of subvalence correlation

by: Mark A Iron, Mikhal Oren, Jan M Martin

Molecular Physics, Vol. 101, No. 9. (2003), pp. 1345-1361.

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Abstract

Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na, Mg, K, and Ca are proposed. The basis sets are validated by calculating spectroscopic constants of a variety of diatomic molecules involving these elements. Neglect of (3s,3p) correlation in K and Ca compounds will lead to erratic results at best, and chemically nonsensical ones if chalcogens or halogens are present. The addition of low-exponent p functions to the K and Ca basis sets is essential for the smooth convergence of molecular properties. Inclusion of inner-shell correlation is important for accurate spectroscopic constants and binding energies of all the compounds. In basis set extrapolation/convergence calculations, the explicit inclusion of alkali and alkaline earth metal subvalence correlation at all steps is essential for K and Ca, strongly recommended for Na, and optional for Li and Mg, while in Be compounds an additive treatment in a separate 'core correlation' step is probably sufficient. Consideration of (1s) inner-shell correlation energy in first-row elements requires the inclusion of (2s,2p) 'deep core' correlation energy in K and Ca for consistency. The latter requires special CCVnZ 'deep core correlation' basis sets. For compounds involving Ca bound to electronegative elements, additional d functions in the basis set are strongly recommended. For optimal basis set convergence in such cases, we suggest the sequence CV(D+3d)Z, CV(T+2d)Z, CV(Q+d)Z, and CV5Z on calcium.

@article{citeulike:3042606, abstract = {Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na, Mg, K, and Ca are proposed. The basis sets are validated by calculating spectroscopic constants of a variety of diatomic molecules involving these elements. Neglect of (3s,3p) correlation in K and Ca compounds will lead to erratic results at best, and chemically nonsensical ones if chalcogens or halogens are present. The addition of low-exponent p functions to the K and Ca basis sets is essential for the smooth convergence of molecular properties. Inclusion of inner-shell correlation is important for accurate spectroscopic constants and binding energies of all the compounds. In basis set extrapolation/convergence calculations, the explicit inclusion of alkali and alkaline earth metal subvalence correlation at all steps is essential for K and Ca, strongly recommended for Na, and optional for Li and Mg, while in Be compounds an additive treatment in a separate 'core correlation' step is probably sufficient. Consideration of (1s) inner-shell correlation energy in first-row elements requires the inclusion of (2s,2p) 'deep core' correlation energy in K and Ca for consistency. The latter requires special CCVnZ 'deep core correlation' basis sets. For compounds involving Ca bound to electronegative elements, additional d functions in the basis set are strongly recommended. For optimal basis set convergence in such cases, we suggest the sequence CV(D+3d)Z, CV(T+2d)Z, CV(Q+d)Z, and CV5Z on calcium.}, author = {Iron, Mark A. and Oren, Mikhal and Martin, Jan M. }, citeulike-article-id = {3042606}, doi = {http://dx.doi.org/10.1080/0026897031000094498}, journal = {Molecular Physics}, keywords = {methodology}, number = {9}, pages = {1345--1361}, posted-at = {2008-07-25 14:12:16}, priority = {2}, publisher = {Taylor \& Francis}, title = {Alkali and alkaline earth metal compounds: core-valence basis sets and importance of subvalence correlation}, url = {http://dx.doi.org/10.1080/0026897031000094498}, volume = {101}, year = {2003} }

RIS record

TY - JOUR ID - citeulike:3042606 L3 - citeulike-article-id:3042606 TI - Alkali and alkaline earth metal compounds: core-valence basis sets and importance of subvalence correlation JF - Molecular Physics VL - 101 IS - 9 SP - 1345 EP - 1361 PB - Taylor & Francis N2 - Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na, Mg, K, and Ca are proposed. The basis sets are validated by calculating spectroscopic constants of a variety of diatomic molecules involving these elements. Neglect of (3s,3p) correlation in K and Ca compounds will lead to erratic results at best, and chemically nonsensical ones if chalcogens or halogens are present. The addition of low-exponent p functions to the K and Ca basis sets is essential for the smooth convergence of molecular properties. Inclusion of inner-shell correlation is important for accurate spectroscopic constants and binding energies of all the compounds. In basis set extrapolation/convergence calculations, the explicit inclusion of alkali and alkaline earth metal subvalence correlation at all steps is essential for K and Ca, strongly recommended for Na, and optional for Li and Mg, while in Be compounds an additive treatment in a separate 'core correlation' step is probably sufficient. Consideration of (1s) inner-shell correlation energy in first-row elements requires the inclusion of (2s,2p) 'deep core' correlation energy in K and Ca for consistency. The latter requires special CCVnZ 'deep core correlation' basis sets. For compounds involving Ca bound to electronegative elements, additional d functions in the basis set are strongly recommended. For optimal basis set convergence in such cases, we suggest the sequence CV(D+3d)Z, CV(T+2d)Z, CV(Q+d)Z, and CV5Z on calcium. KW - methodology AU - Iron, Mark AU - Oren, Mikhal AU - Martin, Jan PY - 2003/// UR - http://dx.doi.org/10.1080/0026897031000094498 ER -

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