Spin-dependent electronic structure in the vicinity of Fe atom in rubredoxin

The fine structure of X-ray absorption spectrum of Fe in rubredoxin was int erpreted on the basis of the multiple scattering theory and the results of calculations of the self-consistent potential. For biological molecules, su ch calculations were made for the first time. It was found that the Fe-S in teraction is the main factor, which determines the electronic structure of the protein active center. The changes in spectrum shape are mostly due to the spin configuration of 3d-electrons. It was shown that the dipole transi tion element significantly changes near the absorption edge; therefore, it is impossible to determine the distribution of unoccupied electronic p-stat es directly from experiment. However, the results of calculations obtained in this work are consistent with the corresponding experimental data, indic ating the adequacy of the calculated densities of free electronic states.