DETERMINATION OF HIGHLY EXCITED-STATES OF DIATOMIC-MOLECULAR IONS USING EXACT H-2(+)-LIKE ORBITALS

A simple configuration-interaction method to calculate accurate electronic energies of two-electron molecular ions at intermediate internuclear distances is presented. The correlated basis functions are constructed from exact H2+ molecular orbitals, and include an explicit dependence on the interelectronic distance in order to describe the cusp conditions of the Coulombic field. An important simplification of the Hamiltonian matrix elements is deduced. The method is applied to determine new potential curves of highly excited states of He22+ molecular ions dissociating into two excited fragments. The g1 state dissociating into He+(2p)+He+(2p) presents a deep well located at R=5.0 a.u., where metastable states can survive. These states could be of interest in excimer lasers. © 1995 The American Physical Society.