High temperature free energy of the Schrodinger model of ferromagnetism for arbitrary single-ion contributions

Abstract

A system is considered described by the hamiltonian H=-J Sigma (i,j) Pij- Sigma i=1N Qi( zeta ) where the first term corresponds to the Schrodinger spin S exchange model and the second term represents an arbitrary single-ion contribution (characterized by the set of parameters zeta ). Terms in the free energy through (J/kBT)7 have been obtained for the face-centered cubic, body-centred cubic, simple cubic, plane triangular and plane square lattices, explicit results for the face-centred cubic lattice are given.