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arXiv 1002.2589cond-mat.mtrl-scicond-mat.other
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GW-RPA近似中的相关能泛函:精确形式、近似形式和挑战

The correlation energy functional within the GW-RPA approximation: exact forms, approximate forms and challenges

Sohrab Ismail-Beigi

摘要:

在原则上,Luttinger-Ward Green函数形式主义允许人们从第一性原理同时计算多体电子系统的总能量和准粒子能带结构。我们提出的GW-RPA近似内的相关能量的近似和精确的表达式,更适合于计算,并允许开发有效的近似的自能算子和相关能量。确切的形式是等离子体激元和带间能量之间的差异的总和。近似形式是基于对屏蔽带间跃迁求和。我们还表明,盲目的极值,这样的泛函导致非物理的结果:施加物理约束的允许的解决方案(格林函数)是必要的。最后,我们提出了一些相关的原子系统的数值结果。

英文摘要:

In principle, the Luttinger-Ward Green's function formalism allows one to compute simultaneously the total energy and the quasiparticle band structure of a many-body electronic system from first principles. We present approximate and exact expressions for the correlation energy within the GW-RPA approximation that are more amenable to computation and allow for developing efficient approximations to the self-energy operator and correlation energy. The exact form is a sum over differences between plasmon and interband energies. The approximate forms are based on summing over screened interband transitions. We also demonstrate that blind extremization of such functionals leads to unphysical results: imposing physical constraints on the allowed solutions (Green's functions) is necessary. Finally, we present some relevant numerical results for atomic systems.

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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