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arXiv 1302.6473physics.chem-ph
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沿绝热联络的双杂化密度泛函分析

Analysis of double hybrid density-functionals along the adiabatic connection

Yann Cornaton, Odile Franck, Andrew M. Teale, Emmanuel Fromager

摘要:

我们提出了一个图形分析的绝热连接的双杂交密度泛函方法,采用二阶微扰理论。近似绝热连接公式的建设有关的这些泛函推导和比较直接使用精确的从头算方法计算。近似绝热被积函数的不连续性被强调,不连续性发生在相互作用强度,这标志着区域之间的过渡:(i)主要由二阶微扰理论描述,(ii)由密度泛函和二阶微扰理论贡献的混合物描述,(iii)纯粹由密度泛函理论描述。数值例子的选择小分子系统和范德华二聚体。在绝热连接的三个部分中的每一个中常用的近似的影响进行了讨论,随着改进的双混合动力方法的发展可能的路线。

英文摘要:

We present a graphical analysis of the adiabatic connections underlying double-hybrid density-functional methods that employ second-order perturbation theory. Approximate adiabatic connection formulae relevant to the construction of these functionals are derived and compared directly with those calculated using accurate ab initio methods. The discontinuous nature of the approximate adiabatic integrands is emphasized, the discontinuities occurring at interaction strengths which mark the transitions between regions that are: (i) described predominantly by second- order perturbation theory (ii) described by a mixture of density-functional and second-order perturbation theory contributions and (iii) described purely by density-functional theory. Numerical examples are presented for a selection of small molecular systems and van der Waals dimers. The impacts of commonly used approximations in each of the three sections of the adiabatic connection are discussed along with possible routes for the development of improved double-hybrid methodologies.

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