Development of the Band Calculation based on the Dynamical Mean Field Theory

本课题的主要目的是发展通用的基于动态平均场理论的能带计算方法，并研究强相关电子系统的相关现象。(1)提出了一种NCAf2v'方法来解决辅助单站点近藤问题。这使我们能够通过f1-f2价波动和f1-f0波动来包含正确的交换过程。通常的NCA方法限制了后者。(2)结合LMTO和NCAf2v法开发了波段计算程序。自能的自旋轨道分裂（SO）和晶体场分裂（CF）也被计算在内。(3)该方法适用于Ce金属和CeSb。在Ce金属的y相中，CF的分裂能大于近藤温度，而在a相中，近藤温度大于CF的分裂能。在光发射光谱中，SO侧峰变得明显，与实验结果相似。在CeSb中再现了PBS的双峰结构。预计近藤温度会更高，因为有效杂化中的费米能量出现了一个小峰，这是由强相关的4f带引起的。研究了三维金属的磁性合金问题。居里温度受相关型波动效应的影响而降低。基于再现能带结构主要特征的紧密结合模型，研究了近藤绝缘子材料YbB12的光学和热电效应。研究了pross12等多极有序系统的动力学激励。

The main purposes of this project were to development the band calculation method based on the dynamical mean field theory for general use, and to study related phenomena of strongly correlated electron systems.(1) A method named as NCAf2v' was developed to solve the auxiliary single site Kondo problem. This enables us to include the correct exchange process through the f1-f2 valence fluctuation along with the f1-f0 fluctuation. The usual NCA method restricts the latter one.(2) The band calculation program was developed by the combination of the LMTO and the NCAf2v' method. The spin-orbit (SO) splitting and the crystalline filed splitting (CF) of the self energy were included in the calculation.(3) The method was applied to Ce metal and CeSb.In the y-phase of Ce metal, the CF splitting energy is larger than the Kondo temperature, while in the a-phase the Kondo temperature is larger than the CF splitting. The SO side peak becomes conspicuous in photo-emission-spectra similarly to the experimental results.In CeSb two peaks structure of PBS was reproduced. A rather higher Kondo temperature is expected because a small peak appears at the Fermi energy in the effective hybridization, which is caused by the strongly correlated 4f band.The magnetic alloy problem of 3d metals was also studied. The Curie temperature id decreased by the correlation type fluctuation effects.The optical and thermoelectric effects of Kondo insulator materials such as YbB12 were studied based on the tight biding model which reproduces the main features of band structures.The dynamical excitation of multipolar ordering systems such as PrOs4Sb12 was also studied.