Kyoto University · Physics and Astronomy
Professor Kimihiko Hirao's research lab specializes in theoretical and computational quantum chemistry, with a focus on advanced electron correlation methods and electronic structure theory. The lab develops and applies multireference perturbation theories, such as multireference Møller-Plesset (MR-MP) methods, to accurately describe complex electronic states and potential energy surfaces in diatomic molecules like N₂. Another key direction involves the variational principles underlying self-consistent field (SCF) methods, particularly in deriving and validating correct orbital equations and coupling operators. The lab also explores photophysical phenomena in rare-earth-doped materials, including persistent spectral hole burning in rare-earth-doped glasses, which has implications for optical data storage and quantum memory technologies.
Figures are computed from collected data and may differ slightly.
A multireference Møller-Plesset (MR-MP) perturbation method, at the second-order level, is applied to the potential energy curve of the ground state of N2, for comparison with a variety of standard ab initio methods. In spite of the drastic simplification, the MR-MP results are very reliable. The energy errors are almost independent of geometry, allowing unbiased treatment of potential energy curves. The potential efficiency and accuracy of the MR-MP approach are emphasized. © 1992 John Wiley &
We have shown that the correct variational equations for the general SCF orbitals are [Fi−Σj |ψj〉 〈 ψj |Gji] |ψi〉=0, where Gji=λjiFj+(1−λji)Fi; λji≠ 0 and how these may be combined into simple eigenvalue problems. In the course of discussions, we re-examined whether the coupling operators suggested previously are based on the correct variational conditions.
Persistent spectral hole burning in Sm2+-doped borate glasses is observed at room temperature. The possible number of holes is approximately five times larger than in halide glass systems because of the larger inhomogeneous linewidth and smaller hole width of borate glass. In this system the photoionization of trapping electrons other than Sm ions at a site is likely to be dominant because of the absence of an antihole adjacent to the hole.
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