On the ground-state spectroscopic constants of Tl-2

The ground-state R-e, omega(e), and D-e of Tl-2 are evaluated using the mul tireference Kramers' restricted configuration interaction method with relat ivistic effective core potential and spin-orbit operators. The best compute d (estimated) values are 3.11 (3.05) Angstrom, 75 (79) cm(-1), and 0.34 (0. 38) eV. These results are in accordance with the Raman experimental data of 3.0 Angstrom, 78 cm(-1), and 0.43 +/- 0.04 eV(D-0) for R-e, omega(e), and D-e, respectively. The relevant treatment for nondynamic correlations is ne cessary to obtain reliable spectroscopic constants, although the spin-orbit operators are introduced from the Hartree-Fock stage. (C) 2000 American In stitute of Physics. [S0021-9606(00)31021-2].