Europium dimer: Van der Waals molecule with extremely weak antiferromagnetic spin coupling

Abstract

High-level ab initio calculations reveal that the Eu2 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 +∑g1 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. © 2009 American Institute of Physics.