ACCURATE POTENTIAL ENERGY CURVES FOR THE GROUND ELECTRONIC STATES OF NeH$^{+}$ AND ArH$^{+}$

Abstract

All available microwave and infrared spectroscopic line positions for the ground electronic states of the molecular cations NeH$^{+}$ and ArH$^{+}$ were employed in a direct potential fitting procedure to determine compact analytical potential curves and radial functions describing breakdown of the Born-Oppenheimer approximation. For NeH$^{+}$, $17$ adjustable parameters were required to represent a total of $183$ line positions for $4$ isotopologues, whereas for ArH$^{+}$, $23$ adjustable parameters were required to represent $440$ line positions for $6$ isotopologues. The MLR$3$ potential energy functional form was employed, taking full account of the proper $1/r{^4}$ limiting long-range dependence of the ion-atom dispersion energy interactions. Accurate vibrational energies, rotational constants and centrifugal distortion constants have been calculated for both diatomic cations.