OBTAINING MICROHARTREE ACCURACY FOR 2-ELECTRON SYSTEMS WITH RANDOM-TEMPERED GAUSSIAN-TYPE GEMINALS

The ground state energies of the helium atom, H2 molecule, and the HeH + and H3+ molecular ions are calculated, using the variational method and basis sets of explicitly correlated Gaussian-type geminals. These energies are accurate to about 1 μ hartree for He and H2, about 27μ hartrees for HeH +, and an estimated 10 μhartrees for H3+. This accuracy is comparable to that of the Hylleraas-CI method and for diatomics approaches that obtained with explicitly-correlated basis sets in elliptical coordinates. © 1990 American Institute of Physics.