Ab initio study of spectroscopic properties of neutral and single charged MgArn clusters

Abstract

The present work reports on a theoretical study of the electronic structure and the stability of ionic Mg⁺Ar_n and neutral MgAr_n (n=1-4) small clusters. The potential energy curves are described using an approach based on the pseudo-potential model, extended Gaussian basis sets and core polarization potentials. We have used Gaussian basis sets of 8s8p8d2f/8s7p5d2f and 6s5p/5s4p orbitals, respectively for Mg and Ar atoms. The pseudopotentials used here are of the l-dependent semilocal type according to the expression of Barthelat and Durand. For magnesium, a [Mg²⁺] core pseudopotential has been used, whereas argon was treated as a zero-electron atom with all its electrons in the core via an atomic [Ar] core pseudopotential determined previously by Duplaa and Spiegelmann. The same geometry is adopted to calculate the ground and excited states for the clusters investigated. Calculations of electronic states were also made as a function of the number of argon atoms. An attempt to explain the obtained results will be presented.