Two‐parameter exponential‐type basis functions for atomic calculations. II

It is found that ordinary STOs fall off too fast in the atomic region in many cases. A new type of basis set, which is more adaptable to the rather different requirements of the various atomic orbitals in an atom, is developed. The suggested functional form χ(r) = Nrn-1 exp{−α[(βr + 1)1/2 − 1]} contains the STOs as a limiting case. Calculations on a series of atoms from H to Zn show that the new basis gives better results than STOs for equal basis set size. The necessary integrals do not present any problem to evaluate.