Spin-cluster expansion: Parametrization of the general adiabatic magnetic energy surface with ab initio accuracy

Based on the adiabatic approximation, a method for the evaluation of magnetic interactions in solids is presented which includes arbitrarily complex multispin interactions on the atomic level with ab initio accuracy. The spin-cluster expansion method thereby allows the accurate and fast treatment of the energetics of spin-canted systems and of the dynamic and thermodynamic properties in adiabatic approximation. It comprises the cluster expansion method of a generalized Ising model that is frequently employed in alloy theory.