Adiabatic potential-energy surfaces of the H-2(+) ion in a strong magnetic field

We use a recently established and optimized atomic orbital basis set to perform extensive numerical calculations on the hydrogen molecular ion in a strong magnetic field. Many excited electronic states with gerade and ungerade parity as well as their potential-energy curves are investigated for the perpendicular configuration, i.e., for orthogonal internuclear and magnetic-field axes. The main issues of our investigation are the local as well as global topological properties of the potential-energy surfaces of the six energetically lowest electronic states of the H-2(+) ion in a strong magnetic field B=1.0 a.u. Our results show the existence of a variety of different possibilities for the topological behavior of the potential-energy surfaces: for the lowest electronic states the global equilibrium configuration is either the parallel or the perpendicular configuration, which are both distinguished by their higher symmetry. As a major result we observe, for the 3(u) electronic state, the effect of a global symmetry lowering: the global equilibrium configuration of the 3, potential-energy surface is at theta=27 degrees, i.e., a configuration that strongly deviates from the distinct parallel or orthogonal configurations. Examinations of the electronic probability density distributions with varying angle theta reveal the origin of the topological behavior of the different surfaces.