Self-interaction correction and contact hyperfine field

The hyperfine field is a precise and essential probe of the magnetic state of a solid, and of the quality of theoretical core wave functions, but it’s accurate evaluation has proven challenging from first principles. In this work, the self-interaction free potential, suggested recently by Lundin and Eriksson, is applied to the core states in the calculation of the hyperfine field for 3d transition metal ferromagnets Fe, Co, and Ni, and for three Fe compounds. Compared to the local spin density approximation and to its conventional self-interaction corrected form, the new potential functional is found to increase substantially the core contribution to the Fermi contact term, leading to good agreement with measurements for Fe and Co, and significantly better results for iron compounds. Our results strongly suggest that the new functional is more suitable for generating realistic core wave functions to high accuracy for a wide range of materials. The subtle effects resulting from the change of potential functional are also addressed.