Abstract
Iterative boundary perturbation theory is applied to the hydrogen molecule–ion H+2 enclosed in spheroidal boxes with finite and infinite walls. The mechanical pressure dependence of ground state properties such as the equilibrium bond length, the change of electronic kinetic energy, quadrupole moment, and the vibrational force constant are presented and discussed. For the hard box, our results are compared with those calculated by the variational method and it is clear that in this case the boundary perturbation theory gives a better description of ground state properties. The behavior of the new more realistic model of H+2 at high pressures based on the concept of finite potential wall (soft or padded box) is discussed.