Theoretical studies on molecular magnetism and superconductivity with the generalized spin orbital(GSO)

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Electronic, magnetic and optical properties in cluster systems of molecules are very interesting.In theoretical treatment, these commonly belong to strong electronic correlation systems. Thus, studies for spin correlation is strongly needed in order to reveal mechanism of functional magnetic materials. Indeed, in the single molecular magnets which are composed of transition metals, noncollinear magnetism is realized with spin frustration and spin degeneration. However, ordinary UHF and UDFT methods cannot treat such systems, and the GHF and GDFT methods based on generalized spin orbital (GSO) must be developed. In this research project, we approach these theme, through extension of mathematical group theory, developing of program package and custom making of computer system.We extended theoretical framework of GSO and developed program packages for ab initio calculation for noncollinear magnets. For example, ab initio HF (GHF), GSO-LDA, GSO-GGA, GSO-LSDA+SIC and GSO-GW methods are suitable for these purpose. Using these methods, the following points were made clear : (1)2- and 3- dimensional spin structure is most stable in both spin frustration and spin degenerate systems. (2)2-dimensinal spin structure is important, when triplet oxygen molecules are dissociated into two oxygen atoms. In addition, we applied them to many model systems.Magnetic parameters (effective exchange integral (J), anisotropic parameter (D)) are essential for investigation of magnetic properties and can be evaluated by ab initio calculation. In this study, evaluation scheme for both J and D values in noncollinear systems is developed.