BASIS-SET-FREE LOCAL DENSITY-FUNCTIONAL CALCULATIONS OF GEOMETRIES OFPOLYATOMIC-MOLECULES

Geometries of 61 small, neutral, singlet-ground-state molecules have b een calculated using the local spin-density approximation (LSDA) densi ty-functional theory. The computational method employed [A. D. Becke, Int. J. Quantum Chem. S 23, 599 (1989)] is free of conventional LCAO b asis-set error. Errors due to basis-set truncation in previously publi shed LSDA geometries are thus distinguished from errors purely due to the LSDA. It is found that the LSDA consistently overestimates bond le ngths between hydrogens and main-group elements by 0.01-0.04 bohr, and usually underestimates bond lengths between nonhydrogens by less than 0.05 bohr. The tabulated geometries should be useful in calibrating b asis sets and in developing beyond-LSDA exchange-correlation functiona ls.