Zurek Eva, Jepsen Ove, Andersen Ole Krogh
Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569, Stuttgart, Germany.
Chemphyschem. 2005 Sep 5;6(9):1934-42. doi: 10.1002/cphc.200500133.
Herein, we outline a method that is able to generate truly minimal basis sets that accurately describe either a group of bands, a band, or even just the occupied part of a band. These basis sets are the so-called NMTOs, muffin-tin orbitals of order N. For an isolated set of bands, symmetrical orthonormalization of the NMTOs yields a set of Wannier functions that are atom-centered and localized by construction. They are not necessarily maximally localized, but may be transformed into those Wannier functions. For bands that overlap others, Wannier-like functions can be generated. It is shown that NMTOs give a chemical understanding of an extended system. In particular, orbitals for the pi and sigma bands in an insulator, boron nitride, and a semimetal, graphite, will be considered. In addition, we illustrate that it is possible to obtain Wannier-like functions for only the occupied states in a metallic system by generating NMTOs for cesium. Finally, we visualize the pressure-induced s-->d transition.
在此，我们概述了一种能够生成真正最小基组的方法，该基组能准确描述一组能带、一条能带，甚至仅仅是一条能带的占据部分。这些基组就是所谓的NMTO，即N阶 muffin-tin轨道。对于一组孤立的能带，NMTO的对称正交归一化会产生一组以原子为中心且通过构造实现局域化的Wannier函数。它们不一定是最大局域化的，但可以转化为那些Wannier函数。对于与其他能带重叠的能带，可以生成类Wannier函数。结果表明，NMTO能对扩展体系给出化学理解。特别地，将考虑绝缘体氮化硼和半金属石墨中π和σ能带的轨道。此外，我们还说明通过为铯生成NMTO，有可能仅在金属体系的占据态中获得类Wannier函数。最后，我们直观展示了压力诱导的s→d跃迁。
