Tran Henry K, Van Voorhis Troy, Thom Alex J W
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
J Chem Phys. 2019 Jul 21;151(3):034112. doi: 10.1063/1.5096177.
A new framework based on density matrix embedding theory (DMET) capable of directly targeting excited electronic states is proposed and implemented. DMET has previously been shown to be an effective method of calculating the ground state energies of systems exhibiting strong static correlation but has never been applied to calculate excited state energies. In this work, the Schmidt decomposition is applied directly on excited states, approximated by higher lying self-consistent field solutions. The DMET prescription is applied following this Schmidt decomposition allowing for a direct embedding of excited states. Initial results are obtained for a system of multiple hydrogen dimers and the lithium hydride dissociation. We analyze the nature of each part of the excited state DMET calculation and identify challenges. These challenges to the implementation of excited state DMET are discussed, and potential suggestions moving forward are recommended.
提出并实现了一种基于密度矩阵嵌入理论（DMET）的能够直接针对激发电子态的新框架。DMET此前已被证明是计算表现出强静态关联系统基态能量的有效方法，但从未应用于计算激发态能量。在这项工作中，施密特分解直接应用于激发态，由较高能级的自洽场解近似。在这种施密特分解之后应用DMET方法，从而实现激发态的直接嵌入。获得了多个氢二聚体系统和氢化锂解离的初步结果。我们分析了激发态DMET计算各部分的性质并识别出挑战。讨论了激发态DMET实施中的这些挑战，并提出了未来可能的建议。
