title: Polarization of core orbitals and computation of nuclear quadrupole coupling constants using Gaussian basis sets.
abstract: Most standard Gaussian basis sets for first row atoms, even large sets designed to converge on a 'complete basis set' limit, systematically overestimate the electric field gradient at nuclear sites for first row atoms, resulting in errors of up to 15% in the computation of nuclear quadrupole coupling constants. This error results from a failure to include tight d functions, which permit the core 1s orbitals to distort under the influence of the field of the nuclear quadrupole. Augmentation of standard basis sets with a single set of single-exponent d functions, matched to the reciprocal square of the nominal 1s radius, reduces these errors by up to 90%.
authors.affiliation: Department of Chemistry, University of Nebraska at Lincoln, Lincoln, NE 68588-0304, United States. Electronic address: gharbison1@unl.edu.
authors.forename: Gerard S
authors.initials: GS
authors.lastname: Harbison
mesh_terms: D000465:Algorithms; D004574:Electromagnetic Fields; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000706:statistics & numerical data; D016011:Normal Distribution; D011789:Quantum Theory
chemical_list: D006859:Hydrogen
keywords: Ab initio calculations; Electric field gradient; NMR; Nuclear quadrupole coupling; Rotational spectroscopy