Crowley Jason M, Tahir-Kheli Jamil, Goddard William A
Materials and Process Simulation Center, MC139-74, California Institute of Technology , Pasadena, California 91125, United States.
J Phys Chem Lett. 2015 Oct 1;6(19):3792-6. doi: 10.1021/acs.jpclett.5b01586. Epub 2015 Sep 10.
It has been established experimentally that Bi2Te3 and Bi2Se3 are topological insulators, with zero band gap surface states exhibiting linear dispersion at the Fermi energy. Standard density functional theory (DFT) methods such as PBE lead to large errors in the band gaps for such strongly correlated systems, while more accurate GW methods are too expensive computationally to apply to the thin films studied experimentally. We show here that the hybrid B3PW91 density functional yields GW-quality results for these systems at a computational cost comparable to PBE. The efficiency of our approach stems from the use of Gaussian basis functions instead of plane waves or augmented plane waves. This remarkable success without empirical corrections of any kind opens the door to computational studies of real chemistry involving the topological surface state, and our approach is expected to be applicable to other semiconductors with strong spin-orbit coupling.
实验已经证实，Bi2Te3和Bi2Se3是拓扑绝缘体，其零带隙表面态在费米能量处呈现线性色散。诸如PBE之类的标准密度泛函理论（DFT）方法对于这种强关联系统会导致带隙出现较大误差，而更精确的GW方法在计算上过于昂贵，无法应用于实验研究的薄膜。我们在此表明，混合B3PW91密度泛函对于这些系统能产生与GW相当的结果，且计算成本与PBE相当。我们方法的效率源于使用高斯基函数而非平面波或增强平面波。这种无需任何经验修正的显著成功为涉及拓扑表面态的真实化学计算研究打开了大门，并且我们的方法有望适用于其他具有强自旋 - 轨道耦合的半导体。
