Orbit-orbit molecular integrals over Gaussian orbitals

Analytical formulas are derived for integrals of the orbit-orbit operator in the Breit-Pauli Hamiltonian. The present method differs from an earlier one in the introduction of a new auxiliary function G_n(a) which is an integral of Shavitt's F_m(t) function. A method for its evaluation is discussed and some numerical examples are given.