Dynamical mean-field approach with predictive power for strongly correlated materials
Dynamical mean-field approach with predictive power for strongly correlated materials
复制标题
具有强相关材料预测能力的动态平均场方法
DOI：
10.1140/epjst/e2017-70078-x
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
A. Lichtenstein
中科院分区：
文献类型：
--
作者：
D. Vollhardt;A. Lichtenstein
已知固体中的电子相关性会导致新的、意想不到的现象的出现，这些现象不仅对基础研究感兴趣，而且在技术应用上也具有巨大的潜力。因此，非常需要适当的理论技术，允许相关电子材料的准确探索。在很长一段时间里，相关材料的第一性原理研究是遥不可及的。在此期间，固体的电子性质由两个基本上独立的团体研究，一个采用密度泛函理论（DFT），另一个使用多体技术研究模型哈密顿。在这里，动态平均场理论（DMFT），其发展开始于25年前，开辟了新的视角。与单粒子理论相反，DMFT的平均场是能量依赖的，即，充满活力。从而充分考虑了镀液对杂质的局域量子涨落。DMFT的唯一近似是忽略空间波动。因此，DMFT为相关晶格模型的研究提供了一个全面的理论框架，并可以描述，例如，波动的时刻，重整化的准粒子，和相关诱导的低和高能量状态之间的光谱重量转移。为了超越模型研究并研究具有强关联电子的真实的材料，20年前开始将局域密度近似（LDA）中的DFT与多体DMFT相结合，即所谓的“LDA+DMFT”方法。从能带结构理论出发，考虑到局部相关性的相互作用项，特别是可以参数化的哈伯德U和Hund的规则耦合J。由此产生的耦合，自洽LDA+DMFT方程数值求解，通常采用量子蒙特-卡罗技术。
Electronic correlations in solids are known to lead to the emergence of novel, unexpected phenomena, which are not only of interest for fundamental research but also have a great potential for technological applications. Hence there is a great need for appropriate theoretical techniques that allow for an accurate exploration of correlated electron materials. For a long time first-principles investigations of correlated materials were out of reach. During that time the electronic properties of solids were investigated by two essentially separate communities, one employing density functional theory (DFT), the other studying model Hamiltonians using many-body techniques. Here the Dynamical Mean-Field Theory (DMFT), whose development started more than 25 years ago, opened new perspectives. In contrast to single-particle theories the mean-field of the DMFT is energy dependent, i.e., dynamical. Thereby the local quantum fluctuations on the impurity due to the bath are fully taken into account. The only approximation of the DMFT is the neglect of spatial fluctuations. Thus DMFT provides a comprehensive theoretical framework for the investigation of correlated lattice models and can describe, for example, fluctuating moments, the renormalization of quasiparticles, and the correlation induced spectral-weight transfer between lowand high-energy states. To go beyond model studies and investigate real materials with strongly correlated electrons, the combination of DFT in the local density approximation (LDA) with the many-body DMFT, the so-called “LDA+DMFT” approach, was initiated 20 years ago. Starting from band structure theory, local correlations are taken into account by interaction terms which can be parametrized in particular by the Hubbard U and the Hund’s rule coupling J . The resulting coupled, self-consistent LDA+DMFT equations have to be solved numerically, usually by employing quantum Monte-Carlo techniques.