The basis set convergence of the Hartree-Fock energy for H2

By using completely optimized basis functions, it is shown that the Hartree-Fock energy for the H-2 molecule converges exponentially, both with respect to the number of basis functions of a given type and with respect to the highest angular momentum functions included. With a basis set including up to h-functions, a subnanohartree accuracy can be obtained. These results clearly suggest that estimation of the complete basis-set limit should employ different extrapolation schemes for the Hartree-Fock and correlation energies. (C) 1999 American Institute of Physics. [S0021-9606(99)30114-8].