Downfolding and N-ization of Basis Sets of Slater Type Orbitals

摘要

We outline a method [1] used to generate a truly minimal basis set in which a single, localized function accurately describes an electron pair. Such a basis is obtained by downfolding a large, conventional basis and subsequently removing the energy dependence via polynomial approximation (N-ization). Starting from SZ (single-ξ), DZ (double-ξ), TZP (triple-ξ with polarization functions), and TZ2P (triple-ξ with two polarization functions) basis sets with respectively 36,66,150 and 186 STOs (Slater type orbitals) for C_6H_6, we demonstrate how for each set, we can generate 15 localized, atom-centered basis functions, STO(N)s, which span the 15 occupied valence states with increasing accuracy for increasing N.