| Research Abstract |
This project is focused on the role of Coulomb interaction in non-magnetic f-electron systems, particularly quadrupole ordered states and singlet ground states, where the effects of the large Coulomb interaction appear even in the ground states in one-particle picture. Therefore the electronic bandstructures are calculated and compared to the experimental results obtained from the dHvA effects and/or XPS etc. by using the FLAPW source codes developed for the LDA+U method.
During the three-year project, the LDA+U method has been generalized to the case including the spin-orbit interaction and the source code has been modified for self-consistent density matrix treatment. It was applied to the singlet ground state in Pr-metal, SmB_6, UPd_3 and PrRu_4P_<12> etc. Then, it has been revealed that there are stable solutions with strong anisotropic f electron charge density in CeRu_2Si_2, UAl_3 and YbB_<12>. Moreover, a preliminary calculation for quadrupole ordered PrPb_3 has been done, showing that the improved LDA+U method can be applied in describing quadrupole ordered states.
The conventional LDA calculations have been also performed to investigate the effects expected with the LDA+U method. The electronic bandstructures and Fermi surface of CeIrIn_5, CeRhIn_5, CeCoIn_5 and LaRu_4Sb_<12> etc. are calculated and compared to the experimental results.
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