EXTRAPOLATED BORN-OPPENHEIMER ENERGY FOR THE GROUND-STATE OF THE HYDROGEN MOLECULE

Ground state energy of the hydrogen molecule, at the equilibrium inter nuclear separation, has been computed in the Born-Oppenheimer approxim ation. The generalized James-Coolidge expansion has been used for the variational wave function. The expansion length has been systematicall y extended, and from the results a limiting value of the energy has be en obtained which is by 0.009 cm(-1) lower than the best variational v alue. Improved agreement is obtained with experimental values of the i onization potential for H-2 and HD. For D-2 the disagreement between t heoretical and experimental values of the ionization potential seems t o be significant.