arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1606.00515physics.comp-phcs.NAmath.NAphysics.chem-ph
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PEXSI-Σ:一种用于Kohn-Sham密度泛函理论的Green函数嵌入方法

PEXSI-$Σ$: A Green's function embedding method for Kohn-Sham density functional theory

The Pennsylvania State University(宾夕法尼亚州立大学);University of California, Berkeley(加州大学伯克利分校);Lawrence Berkeley National Laboratory(劳伦斯伯克利国家实验室);Duke University(杜克大学)

Xiantao Li, Lin Lin, Jianfeng Lu

AI总结:

本文提出PEXSI-Σ方法,通过近最优选择的Green函数在复杂系统中实现KSDFT计算,具有O(N²)的计算复杂度,且与原子Green函数方法兼容。

摘要:

本文提出了一种名为PEXSI-Σ的Green函数嵌入方法,用于在Kohn-Sham密度泛函理论框架内描述复杂系统。该方法通过在复频域评估一组近最优选择的Green函数来近似密度矩阵。每个Green函数的复边界条件由从物理参考Green函数构造的自能矩阵Σ描述,该矩阵可通过相对简单的方式计算。在线性区域内,此类边界条件的处理可以数值上精确。Σ矩阵的支持被限制在计算域边界附近的自由度上,可以被解释为频率依赖的表面势。这使得能够在O(N²)的计算复杂度下进行KSDFT计算,其中N是计算域内原子的数量。Green函数嵌入方法也自然与原子Green函数方法兼容,以放松计算域外的原子构型。作为概念验证,我们使用DFTB+软件包展示了PEXSI-Σ方法在具有空位和位错偶极子型缺陷的石墨烯中的准确性。

英文摘要:

In this paper, we propose a new Green's function embedding method called PEXSI-$Σ$ for describing complex systems within the Kohn-Sham density functional theory (KSDFT) framework, after revisiting the physics literature of Green's function embedding methods from a numerical linear algebra perspective. The PEXSI-$Σ$ method approximates the density matrix using a set of nearly optimally chosen Green's functions evaluated at complex frequencies. For each Green's function, the complex boundary conditions are described by a self energy matrix $Σ$ constructed from a physical reference Green's function, which can be computed relatively easily. In the linear regime, such treatment of the boundary condition can be numerically exact. The support of the $Σ$ matrix is restricted to degrees of freedom near the boundary of computational domain, and can be interpreted as a frequency dependent surface potential. This makes it possible to perform KSDFT calculations with $\mathcal{O}(N^2)$ computational complexity, where $N$ is the number of atoms within the computational domain. Green's function embedding methods are also naturally compatible with atomistic Green's function methods for relaxing the atomic configuration outside the computational domain. As a proof of concept, we demonstrate the accuracy of the PEXSI-$Σ$ method for graphene with divacancy and dislocation dipole type of defects using the DFTB+ software package.

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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