Abstract
Our method for the solution of the molecular Schrödinger equation has been further developed and extended to the case of the four‐electron system. Ab initio calculations are presented which lead to the electronic wavefunctions and energies of square and rectangular forms of H4. As a preliminary to the four‐electron studies, the energies and wavefunctions for a number of states of the ions H43+ and H42+ are calculated. Complete contour maps for the potential energy surfaces of these systems are reported and the H4 surface is discussed in connection with the bimolecular isotope exchange reaction H2+D2→2HD. Contour maps for the electron density distribution in square and rectangular H4 are presented and discussed.