title: Physical properties of iron-sulfur Fe6S6 superclusters important for biological systems.
abstract: The theoretical analysis of the thermal and magnetic properties of iron-sulfur superclusters has been studied by taking into account Heisenberg interactions and resonance delocalizations (double exchange interactions). The numerical calculations are based on the determination of the lowest energy states for different values of spins (from S = 0.5 to S = 12.5) and Heisenberg exchange integrals. It is shown that the spin magnetic susceptibility of the iron-sulfur superclusters decreases with increasing temperature and increases with increasing the double exchange parameter. In contrast to the susceptibility, the heat capacity decreases with the increasing values of the double exchange parameter. It was theoretically found that spin of ground state for the iron-sulfur supercluster is equal to 0.5. Based on our results, we can state that the Heisenberg model of spin interactions describes the thermodynamic properties of the iron-sulfur superclusters which are the important constituents of proteins and enzymes.
authors: Materials Science Department, Technical University of Czestochowa, 42 200 Czestochowa, Poland.
authors: Julita
authors: J
authors: Ozga
authors: Marek
authors: M
authors: Matusiewicz
authors: Jacek
authors: J
authors: Kasperczyk
authors: Gregory
authors: G
authors: Kozlowski
authors: Ivan
authors: I
authors: Kityk
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D004574:Electromagnetic Fields; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008956:Models, Chemical; D013455:Sulfur / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D013455:Sulfur; D007501:Iron