Spin and charge densities from Hiller–Sucher–Feinberg identities. Test calculations for He, B, C, N, O, and F atoms and H2O, N2, and CH3 molecules

Spin and charge densities for several atoms and molecules can be calculated by the use of the Hiller–Sucher–Feinberg identities in the Hartree–Fock (HF) or the unrestricted Hartree–Fock (UHF) level with Gaussian basis sets. Previously presented formulas for the necessary integrals are improved for rapid computations when the d‐type Gaussian functions are added to the basis set. For charge density, a reliable description is obtained even for the HF or the UHF wave function, despite the use of the noncusp basis functions. The lack of the cusp in the Gaussian functions can be overcome also for spin density.