Berlin 2001 – scientific programme
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MO: Molekülphysik
MO 7: Posters Wednesday: Theory: Structure and Dynamics
MO 7.9: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT3
Ab initio CALCULATIONS ON MOLECULAR STRUCTURE OF Mg2 — •E. Czuchaj and M. Krośnicki — Institute of Theoretical Physics and Astrophysics, University of Gdańsk, Wita Stwosza 57, 80-952 Gdańsk, Poland
Adiabatic potential energies for the ground state and several low-lying excited states of the Mg2 dimer have been calculated using the ab initio complete-active-space multiconfiguration self-consistent-field (CASSCF)/ complete-active-space multireference second-order perturbation theory (CASPT2) calculations. The calculations were performed by means of MOLPRO program using the contracted (20s14p4d3f2g)/[14s12p4d3f2g] cc-p V5Z orbitals of Dunning for Mg augmented with two diffuse s and p atomic orbitals. In the calculations, 24 electrons of the species were correlated to obtain the X1Σg+, 3Πg, 3Σu, 3Πu, 3Σg, 1Πg, 1Σu, (1)1Πu, (2)1Πu and (2)1Σg potential curves in the internuclear separation range from 3.0 to 40.0 a0. The obtained potential curves are qualitatively similar to the ones calculated earlier by Stevens and Krauss, but some quantitative differences occur. Comparison between the present potential curves and experimentally known X1Σg+ and 1Σu+ energy curves shows very good agreement for both the bond strength De and bond length Re. In general, the present potential curves are considerably deeper than that calculated by Stevens and Krauss, particularly it concerns the (1)1Πu potential curve. In addition, using the Breit-Pauli operator, the spin-orbit coupling between the 1Σu and 3Πu states as well as between the 1Πg and two triplet 3Σg and 3Πg states have been computed as a function of internuclear separation.