Performance of the tau-dependent functionals in predicting the magnetic coupling of ionic antiferromagnetic insulators.

The performance of some kinetic energy density (tau) dependent functionals in predicting the effective Heisenberg exchange has been explored using the KNiF3 and K2NiF4 insulators as case examples. Our results show that this new generation of functionals represents an important improvement with respect to the current local and gradient corrected functionals yielding a semi-quantitative description of the antiferromagnetic coupling without the need of hybrid approaches thus avoiding the calculation of exact, Hartree-Fock exchange. This feature opens a wide field of application especially in solid state. (c) 2004 American Institute of Physics.