Twentieth-Order Perturbation Study of the Nondiabatic Electric Polarizabilities forH2+via the Perturbational-Variational Rayleigh-Ritz Formalism

Abstract

Large-order perturbation theory has been applied, for the first time, to the Stark effect for ${\mathrm{H}}_2^{+}$, yielding the Rayleigh-Schrödinger ground-state eigenvalue (polarizability) series through twentieth order; previous expansions were limited to fourth order. The calculations were performed nonadiabatically (i.e., without invoking the Born-Oppenheimer approximation) by means of the perturbational-variational Rayleigh-Ritz formalism. The leading terms of the Rayleigh-Schrödinger polarizability series so obtained provide the most accurate values thus far determined for ${\alpha }_{\mathrm{zz}}$ and ${\gamma }_{\mathrm{zzzz}}$.