Segmented Gaussian Basis Set

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• order form
• origin of basis sets
• supported atoms and basis sets
• usage
• who we are

Origins of Basis sets

Acronym of the basis sets

all electron basis set

For all-electron basis sets, we provide minimal-type contracted Gaussian-type function (cGTF) sets generated by Tatewaki and Koga in decontracted forms. The minimal-type cGTFs use independent primitive GTFs (pGTFs) for the major component of individual atomic orbitals. They usually have much shorter expansions than GTF sets in general contraction forms. Further, they give us with a clear physical interpretation for molecular electronic structures.

For all-electron relativistic basis sets, we performed HF calculations by using the uncontracted GTFs prepared by Koga and Tatewaki, which were extended for heavy elements, at the DKH3 level with the Gaussian nucleus model. These HF orbitals are supplied in a general contraction form for core orbitals, and in a decontracted form for valence orbitals. It should be noted that these sets would be better to be used at the DKH3 level with a finite nucleus model, since otherwise the BSSE might appear.

Model Core Potential

The model core potential (MCP) is originally proposed by Huzinaga and co-workers and is unique among various types of effective core potential (ECP) methods, where it is capable to produce valence orbitals with nodal structures. Nodeless pseudo-orbitals are well known to cause too large exchange integrals in ECP approaches. The MCP method are suitable to accurately describe the correlation effects of valence orbitals. The major relativistic effects were incorporated in the MCPs for atoms heavier than Ga using the Cowan-Griffin's quasi-relativistic Hartree-Fock method.

NOSeC (Natural Orbital based Segmented Contacted GTF)

Noro and co-workers have developed correlating basis functions of valence electrons for H to Lr, except La and Ac, and core-valence electrons for the alkali and alkaline earth atoms. They used contracted Gaussian-type functions (cGTFs) in a segmented form, whose coefficients and exponents are optimized to minimize the difference from very accurate natural orbitals. The obtained basis functions attain both the efficiency and compactness and showed high quality of describing correlation energies in various atoms and molecules. Relativistic effects are considered for heavy atoms from Cs to Rn by the third order of Douglas-Kroll-Hess (DKH3) approximation. Although these basis sets were developed for all-electron calculations, it was shown that the use of these sets with MCP gives more than 99% of the correlation energies obtained by the atomic natural orbitals optimized for MCP itself.

Historical comments

The Sapporo-(DKH3)-xZP-old sets, tentatively called for during April to June 2012, are renamed back to their original name Sapporo-(DKH3)-xZP sets and are still available from the menu. The Sapporo-(DKH3)-xZP-2012 basis sets include core correlating basis functions for the p-block elements and improve the previous sets for early transition metal elements. The basis sets for the Lanthanide elements are also implemented.

Although we have hitherto used the acronyms DK, DK3, and DKH3 interchangeably in this site, all the present relativistic calculations were performed by the 3rd order of the Douglas-Kroll-Hess approximation. We now unify all the names of the present relativistic basis sets by using DKH3, but the contents of basis sets themselves remain unchanged.

last update : Oct 7, 2014; e-mail : tashi_noro@me.com