Theoretical study of the and transitions in the Cd-rare gas van der Waals molecules

E. Czuchaj; M. Krośnicki; J. Czub

doi:10.1007/s100530170251

2021 Impact factor 1.611

Atomic, Molecular, Optical and Plasma Physics

Eur. Phys. J. D 13, 345-353 (2001)
https://doi.org/10.1007/s100530170251

Theoretical study of the and transitions in the Cd-rare gas van der Waals molecules

E. Czuchaj^a, M. Krośnicki and J. Czub

Institute of Theoretical Physics and Astrophysics, University of Gdańsk, ul. Wita Stwosza 57, 80-952 Gdańsk, Poland

Corresponding author: ^a czu@iftia.univ.gda.pl

Received: 10 August 2000
Revised: 7 November 2000
Published online: 15 March 2001

Abstract

Excitation spectra arising from and electronic transitions in the Cd-rare gas (RG) van der Waals molecules are calculated using newly obtained theoretical potential curves for these species. In the molecular structure calculations, Cd²⁰⁺ and RG⁸⁺ cores are simulated by energy-consistent pseudopotentials which also account for scalar-relativistic effects and spin-orbit (SO) interaction within the valence shell. Potential energies in the coupling scheme have been obtained by means of ab initio complete-active-space multiconfiguration self consistent-field (CASSCF)/complete-active-space multireference second-order perturbation theory (CASPT2) calculations with a total 28 correlated electrons, while the SO matrix has been computed in a reduced CI space restricted to the CASSCF level. The final Ω potential curves are obtained by diagonalization of the modified SO matrix (its diagonal elements before diagonalization substituted for the corresponding CASPT2 eigen-energies). The spectroscopic parameters for the ground and several excited states of the Cd-RG complexes deduced from the calculated potential curves are in quite reasonable agreement with available experimental data. In addition, the radial Schrödinger equation for nuclear motion was solved numerically with the calculated potentials to evaluate the corresponding vibrational levels and radial wavefunctions. The latter have been used in the calculation of the appropriate Franck-Condon factors to yield information on relative intensities of the vibrational bands of the Cd-RG complexes. The theoretical vibrational progressions are discussed in the context of experimental spectra.