Development of the First-Principles Theory of Long-Range Electron Correlations Based on the Nonlocal Effective Medium and Its Application to the Iron Compounds

2016 Fiscal Year Final Research Report

• Project/Area Number: 25400404
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Mathematical physics/Fundamental condensed matter physics
• Research Institution: University of the Ryukyus
• Principal Investigator: KAKEHASHI Yoshiro 琉球大学, 理学部, 教授 (10191975)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: 電子相関 / 第一原理計算 / 運動量依存局所変分理論 / 非対角有効場 / 非局所電子相関 / 鉄系化合物

Outline of Final Research Achievements

The first-principles momentum dependent local ansatz theory has been constructed by combining the momentum dependent local ansatz theory with the first-principles tight-binding LDA+U Hamiltonian. Theory has been applied to the iron-group transition metals from Sc to Cu. It is found that (1) the overestimate of the magnetic energy in the band theory originates in the lack of the Hund energy gain in the paramagnetic state, (2) enhancement of the amplitude of local moments is quantitatively explained by the Hund energy coupling, (3) momentum distribution functions are strongly deviated from the Fermi-Dirac function due to electron correlations in the rate transition metals, and (4) associated mass enhancement factors explain the experimental data of the low temperature specific heats. The theory provides us with a base to construct the first-principles self-consistent projection operator method for nonlocal excitations.

Free Research Field

数物系科学