ACCURATE MULTIPOLE MOMENTS FOR H-2 AND D2 INCLUDING THE EFFECTS OF ELECTRON CORRELATION AND MOLECULAR VIBRATION AND ROTATION

Explicitly correlated Gaussian geminal wavefunctions of the valence bond type are constructed for the ground electronic state of H-2 at 11 different bond lengths between 0.8 a0 and 2.6 a0. The variational potential energy curve is parallel to and about 0.08 cm-1 above the exact one. These wavefunctions are used Lo calculate multipole moments Q(L), up to rank 10, as a function of bond length. Rovibrational averages for selected states and thermal averages for selected temperatures are reported. The effects of isotopic substitution are also considered.