Bulik Ireneusz W, Chen Weibing, Scuseria Gustavo E
Department of Chemistry, Rice University, Houston, Texas 77005, USA.
J Chem Phys. 2014 Aug 7;141(5):054113. doi: 10.1063/1.4891861.
Density matrix embedding theory [G. Knizia and G. K.-L. Chan, Phys. Rev. Lett. 109, 186404 (2012)] and density embedding theory [I. W. Bulik, G. E. Scuseria, and J. Dukelsky, Phys. Rev. B 89, 035140 (2014)] have recently been introduced for model lattice Hamiltonians and molecular systems. In the present work, the formalism is extended to the ab initio description of infinite systems. An appropriate definition of the impurity Hamiltonian for such systems is presented and demonstrated in cases of 1, 2, and 3 dimensions, using coupled cluster theory as the impurity solver. Additionally, we discuss the challenges related to disentanglement of fragment and bath states. The current approach yields results comparable to coupled cluster calculations of infinite systems even when using a single unit cell as the fragment. The theory is formulated in the basis of Wannier functions but it does not require separate localization of unoccupied bands. The embedding scheme presented here is a promising way of employing highly accurate electronic structure methods for extended systems at a fraction of their original computational cost.
密度矩阵嵌入理论[G. 克尼齐亚和G. K.-L. 陈，《物理评论快报》109, 186404 (2012)]和密度嵌入理论[I. W. 布利克、G. E. 斯库塞里亚和J. 杜凯尔斯基，《物理评论B》89, 035140 (2014)]最近已被引入用于模型晶格哈密顿量和分子系统。在本工作中，该形式体系被扩展到无限体系的从头算描述。给出了此类体系杂质哈密顿量的适当定义，并在一维、二维和三维情形中进行了演示，使用耦合簇理论作为杂质求解器。此外，我们讨论了与片段态和浴态解缠相关的挑战。即使使用单个单胞作为片段，当前方法产生的结果也与无限体系的耦合簇计算结果相当。该理论是在万尼尔函数的基础上制定的，但它不需要对未占据能带进行单独的局域化。这里提出的嵌入方案是一种很有前景的方法，能够以扩展体系原始计算成本的一小部分采用高精度电子结构方法。
