Basis set quality vs size. Approximate Gaussian-type orbital (GTO) wave functions for first row transition metal atoms

Energy optimized basis sets ranging from (12, 6, 4) to (16, 11, 8) have been derived for the atoms Sc--Zn. The accuracy of these basis sets compared to numerical calculations range from 603 to 5 mhartree. The varying number of d electrons makes it difficult to establish uniform quality criteria through the series. The largest s2d/sup n/ optimized basis sets also describe s1d/sup n//sup +1/ states reasonably well, but should be augmented by diffuse d functions to describe s0d/sup n//sup +2/ states