MULTIMODE calculations of the infrared spectra of H7+ and D7 + using ab initio potential energy and dipole moment surfaces

Abstract

We present a new ab initio potential energy surface (PES) and a dipole moment surface (DMS) for H+7H7+ in the bound region. The PES is a linear least-squares fit to 42,525 ab initio points whose energies were computed with CCSD(T)-F12b/cc-pVQZ-F12 theory, and the DMS is a fit to dipole moments calculated at MP2 level of theory. The PES and DMS describe the bound region of H+7H7+ precisely. MULTIMODE (MM) calculations of the infrared spectra of H+7H7+ and D+7D7+ were performed using the new PES and DMS. These calculations were carried out at the lowest three stationary points using the single-reference version of MM, and only the five high-frequency modes were considered. The calculated spectra agree well with the recent experimental predissociation action spectra.