arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1603.00512cond-mat.mtrl-sciphysics.comp-ph
收藏

基于亚广义梯度近似的更真实的带隙:仅在广义Kohn-Sham方案中

More-Realistic Band Gaps from Meta-Generalized Gradient Approximations: Only in a Generalized Kohn-Sham Scheme

Zeng-hui Yang, Haowei Peng, Jianwei Sun, John P. Perdew

摘要:

与局域密度近似(LDA)和广义梯度近似(GGA)不同,元广义梯度近似(meta-GGA)的计算通常根据广义Kohn-Sham(gKS)形式主义进行。交换相关势的gKS方程是非乘法的,这阻止了系统的比较元GGA能带结构的LDA和GGA。我们实现了优化的有效势(OEP)的元GGA的周期性系统,这使我们能够进行元GGA计算在相同的KS方式为LDA和GGA。我们将OEP应用于几个元GGA,包括新的SCAN功能[Phys. Rev. Lett. 115,036402(2015)]。我们发现meta-GGAs的KS能隙和KS能带结构与GGAs的接近。它们比偏-GGA的更真实的gKS能隙小,但可能接近精确KS势的能带结构中不太真实的能隙,如通过与EXX+RPA OEP势的能隙比较可以看出的。在OEP计算中,众所周知的元-GGA的网格敏感性要严重得多。

英文摘要:

Unlike the local density approximation (LDA) and the generalized gradient approximation (GGA), calculations with meta-generalized gradient approximations (meta-GGA) are usually done according to the generalized Kohn-Sham (gKS) formalism. The exchange-correlation potential of the gKS equation is non-multiplicative, which prevents systematic comparison of meta-GGA bandstructures to those of the LDA and the GGA. We implement the optimized effective potential (OEP) of the meta-GGA for periodic systems, which allows us to carry out meta-GGA calculations in the same KS manner as for the LDA and the GGA. We apply the OEP to several meta-GGAs, including the new SCAN functional [Phys. Rev. Lett. 115, 036402 (2015)]. We find that the KS gaps and KS band structures of meta-GGAs are close to those of GGAs. They are smaller than the more realistic gKS gaps of meta-GGAs, but probably close to the less-realistic gaps in the band structure of the exact KS potential, as can be seen by comparing with the gaps of the EXX+RPA OEP potential. The well-known grid sensitivity of meta-GGAs is much more severe in OEP calculations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑