A highly accurate potential energy curve for the mercury dimer

Abstract

The potential energy curve of the electronic ground state of the mercury dimer based on CCSD(T) calculations at the complete basis set (CBS) limit, including corrections for the full triples ΔT and explicit spin-orbit (SO) interactions at the CCSD(T) level of theory, is presented. In the far long-range part, the potential energy curve is complemented by symmetry-adapted perturbation theory calculations. Potential curves of an analytically simple, extended Lennard-Jones form are obtained from very accurate fits to the CBS/CCSD (T) +SO and CBS/CCSD (T) +SO+ΔT data. The Hg2 potential curves yield dissociation energies of De =424/392 cm-1 and equilibrium distances of re =3.650/3.679 Å at the CBS/CCSD (T) +SO and CBS/CCSD (T) +SO+ΔT levels of theory, respectively. By including perturbative quadruple corrections in our coupled-cluster calculations and corrections from correlating the 4f-core, we arrive at a final dissociation energy of De =405 cm-1, in excellent agreement with the experimentally estimated value of 407 cm-1 by Greif and Hensel. In addition, the rotational and vibrational spectroscopic constants as well as the second virial coefficient B (T) in dependence of the temperature T are calculated and validated against available experimental and theoretical data. © 2010 American Institute of Physics.