Resonance in the Hydrogen Molecule

In a recent paper (1) Mueller and Eyring have discussed the normal state of the hydrogen molecule with use of a variation function constructed in the usual Heitler-London manner, except with replacement, for each electron, of the hydrogen-atom function about atom a, exp(-Z'ra/ao), byt the more complex function φa = exp(-Z'ra/ao)exp(-Z''rb/a0). The authors call one-electron functions of this sort semilocalized orbitals. They have compared the value of the bond energy calculated for the wave function [...], with those given by the simple atomic orbital method and the molecular orbital method, and have pointed out that there is an improvement to 4.20 ev, from the values 3.76 ev and 3.60 ev, respectivel