Gaussian functions in Hylleraas-configuration interaction calculations. III. Wave functions for the /ital X/ /sup 1//summation//sup +//sub /ital g// state of hydrogen

The Hylleraas-CI method with Cartesian Gaussian basis functions of various sizes has been used to calculate the ground state energies and wave functions for the hydrogen molecule at internuclear distances of 1.0, 1.4011, 4.0, and 8.0 bohr. The best basis sets reproduce energies obtained with the confocal elliptical coordinates by Kolos /ital et/ /ital al/. to within 0.3 cm/sup /minus/1/. A few cross sections of the wave functions are presented graphically, showing clearly that the improvement of Hylleraas-CI over conventional CI is due to the presence of a slightly deeper Coulomb hole around the electrons.