The Dirac equation in the algebraic approximation. IX. Matrix Dirac-Hartree-Fock calculations for the HeH and BeH ground states using distributed Gaussian basis sets

Using large component basis sets of distributed s-type Gaussian functions with positions and exponents optimized so as to support Hartree-Fock total energies with an accuracy approaching the sub-muhartree level, Dirac-Hartree-Fock-Coulomb calculations are reported for the ground states of the open-shell molecular systems HeH and BeH. The small component basis sets are obtained by applying the (strict) kinetic balance condition. Explicit expressions are given for the electron repulsion integrals required for relativistic atomic and molecular electronic structure calculation, using basis sets of distributed G-spinors. (C) 2004 Wiley Periodicals, Inc.