title: Europium dimer: van der Waals molecule with extremely weak antiferromagnetic spin coupling.
abstract: High-level ab initio calculations reveal that the Eu(2) dimer is a van der Waals molecule with extremely weak antiferromagnetic spin coupling. The Heisenberg spin-exchange model, validated by the multireference configuration interaction method, is used to construct the full set of model interaction potentials for the states with the total spin S ranging from 0 to 7 at the coupled cluster level of theory. This model establishes the singlet (1) summation operator(+) (g) state as the ground one of the dimer with the binding energy of 710 cm(-1), the vibrational frequency of 23 cm(-1) and the effective spin-coupling constant J estimated approximately -0.3 cm(-1).
authors.affiliation: Department of Chemistry, Moscow State University, Moscow 119991, Russia. alexei@classic.chem.msu.su
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Buchachenko
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Chałasiński
authors.forename: Małgorzata M
authors.initials: MM
authors.lastname: Szcześniak