Many-electron explicitly correlated Gaussian functions. I. General theory and test results

Abstract

The Gaussian functions containing correlation factors of the type exp(−βrij2), employed so far in variational calculations of two-electron atoms and molecules are generalized for many-electron systems. Explicit formulas for necessary one-, two-, three-, and four-electron integrals over s-type correlated Gaussians are given. Preliminary computations for the H3 and LiH molecules yield significantly lower energy values than all previously published variational results.