dorsal/arxiv
View SchemaAlkali and Alkaline Earth Metal Compounds: Core-Valence Basis Sets and Importance of Subvalence Correlation
| Authors | Mark A. Iron, Mikhal Oren, Jan M. L. Martin |
|---|---|
| Categories | |
| ArXiv ID | physics/0301056 |
| URL | https://arxiv.org/abs/physics/0301056 |
| DOI | 10.1080/0026897031000094498 |
| Journal | Molecular Physics 101, 1345-1361 (2003) |
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 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 inclusion of $(2s,2p)$ `deep core' correlation energy in K and Ca for consistency. The latter requires special CCV$n$Z `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.
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"abstract": "Core-valence basis sets for the alkali and alkaline earth metals Li, Be, Na,\nMg, K, and Ca are proposed. The basis sets are validated by calculating\nspectroscopic constants of a variety of diatomic molecules involving these\nelements. Neglect of $(3s,3p)$ correlation in K and Ca compounds will lead to\nerratic results at best, and chemically nonsensical ones if chalcogens or\nhalogens are present. The addition of low-exponent $p$ functions to the K and\nCa basis sets is essential for smooth convergence of molecular properties.\nInclusion of inner-shell correlation is important for accurate spectroscopic\nconstants and binding energies of all the compounds. In basis set\nextrapolation/convergence calculations, the explicit inclusion of alkali and\nalkaline earth metal subvalence correlation at all steps is essential for K and\nCa, strongly recommended for Na, and optional for Li and Mg, while in Be\ncompounds, an additive treatment in a separate `core correlation\u0027 step is\nprobably sufficient. Consideration of $(1s)$ inner-shell correlation energy in\nfirst-row elements requires inclusion of $(2s,2p)$ `deep core\u0027 correlation\nenergy in K and Ca for consistency. The latter requires special CCV$n$Z `deep\ncore correlation\u0027 basis sets. For compounds involving Ca bound to\nelectronegative elements, additional $d$ functions in the basis set are\nstrongly recommended. For optimal basis set convergence in such cases, we\nsuggest the sequence CV(D+3d)Z, CV(T+2d)Z, CV(Q+$d$)Z, and CV5Z on calcium.",
"arxiv_id": "physics/0301056",
"authors": [
"Mark A. Iron",
"Mikhal Oren",
"Jan M. L. Martin"
],
"categories": [
"physics.chem-ph",
"physics.atom-ph"
],
"doi": "10.1080/0026897031000094498",
"journal_ref": "Molecular Physics 101, 1345-1361 (2003)",
"title": "Alkali and Alkaline Earth Metal Compounds: Core-Valence Basis Sets and Importance of Subvalence Correlation",
"url": "https://arxiv.org/abs/physics/0301056"
},
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