Approximate density-functional calculations of spin densities in large molecular systems and complex solids

We have extended an approximate density-functional based method to the calculation of spin densities and subsequently to electron paramagnetic hyperfine interactions. The isotropic hyperfine coupling constants of protons in molecules are calculated in quantitative agreement with experimental results and ab initio data. Qualitative agreement compared to ab initio data has also been found for other atoms in molecules and solid state systems.