Critical temperature of iron derived from total energy calculations

Abstract

We have performed total energy calculations for iron in the ferromagnetic and in several antiferromagnetic configurations. It is assumed that the functional describing exchange and correlation is the same for the ferromagnetic ground state and the antiferromagnetic states. The calculated total energies are used to obtain the interaction parameters in a Heisenberg model. From this Heisenberg model we derive excited state properties, where one has to keep in mind that the model parameters are directly based on the ground‐state ab initio results. The nearest‐neighbor interaction is ferromagnetic and a model which includes only nearest‐neighbor interactions yields a transition temperature of 1685 K. The next‐nearest‐neighbor interaction, however, is antiferromagnetic and reduces the critical temperature to 895 K. Several other physical quantities derived from our model Heisenberg Hamiltonian are discussed.