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arXiv 1603.01428cond-mat.mtrl-sci
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用高效的密度泛函理论Kohn-Sham方案精确计算半导体电离势

Achieving accurate ionization potential of semiconductors by the efficient Kohn-Sham scheme of density functional theory

Lin-Hui Ye

摘要:

尽管密度泛函理论的Kohn-Sham(DFT-Kohn-Sham)方案在大量的应用中取得了巨大的成功,但由于局域密度近似(LDA)和广义梯度近似(GGA)中的自相互作用误差以及在表面计算中难以使用渐近长程势,DFT-Kohn-Sham方案一直不能得到可靠的半导体电离势(IP)。利用一种近似的优化有效势(OEP),即Becke-Johnson'06交换,探讨了OEP计算半导体激电的能力,并采用了一种既适用于短程势又适用于长程势的表面技术。结合LDA相关性,近似OEP已经实现了17个半导体的IP精度,这是类似于更复杂的$GW$近似(GWA),与计算成本只有LDA/GGA。这是第一次,这开辟了系统计算的半导体IP的DFT-科恩-沙姆计划的方式。$v_{xc}$的长程部分对于固体表面并不像对于原子和分子那样重要,因为波函数主要束缚在平板上,而较少暴露于渐近区域。尽管如此,它对总IP的贡献很大,因此不应简单地忽略。在不包括其影响的情况下,相同的GWA过程不太可能同时实现普遍准确的带隙和准确的IP,如在实际计算中确实看到的那样。

英文摘要:

Despite of its huge successes in vast amount of applications, the Kohn-Sham scheme of density functional theory (DFT-Kohn-Sham) has not been able to get reliable ionization potentials (IP) for semiconductors, due to self-interaction error in the local density approximation (LDA) and generalized gradient approximations (GGA), and the difficulty of using asymptotically long-ranged potentials for surface calculations. An approximate optimize effective potential (OEP), the Becke-Johnson'06 exchange, is used to explore the capability of OEP to calculate semiconductor IP with a surface technique suitable for both short- and long-ranged potentials. Combined with the LDA correlation, the approximate OEP has achieved an IP accuracy for 17 semiconductors which is similar to the much more sophisticated $GW$ approximation (GWA), with the computational cost of only LDA/GGA. For the first time, this opens the way for systematic calculation of semiconductor IP's by the DFT-Kohn-Sham scheme. The long-range part of the $v_{xc}$ is not as important for solid surface as for atoms and molecules since the wave functions are mainly bound to the slab while less exposed to the asymptotic region. Nevertheless, it contributes significantly to the total IP and therefore shall not be simply ignored. Without including its effects, it is unlikely that the same GWA procedure could achieve universally accurate band gaps and accurate IP's at the same time, as is indeed seen in practical 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。

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