论文标题
来自周期性运动方程耦合群集理论的固体中的激子
Excitons in solids from periodic equation-of-motion coupled-cluster theory
论文作者
论文摘要
我们使用基于高斯的周期性方程式耦合群集理论（EOM-CCSD）进行了对三维固体的电子激发态的初始研究。通过Brillouin区域采样和动量保护实施的转化对称性的明确使用负责大大降低成本。我们最大的系统研究了，该系统使用64 k点（4x4x4网格）对布里鲁因区进行采样，对应于640个轨道中768个电子的规范EOM-CCSD计算。我们研究了八个简单的半导体和绝缘子，直接的单线激发能在3至15 eV范围内。与实验相比，我们预测的激发能的平均绝对误差为0.27 eV。我们此外，我们以非零动量计算激子的能量，并将LIF的激子分散与来自非弹性X射线散射的实验数据进行比较。通过计算应变下的激发能，我们提取静液压变形电位，以量化激子和声音声子之间相互作用的强度。我们的结果表明，耦合群集理论是一种准确研究固体中各种激子现象的有前途方法。
We present an ab initio study of electronically excited states of three-dimensional solids using Gaussian-based periodic equation-of-motion coupled-cluster theory with single and double excitations (EOM-CCSD). The explicit use of translational symmetry, as implemented via Brillouin zone sampling and momentum conservation, is responsible for a large reduction in cost. Our largest system studied, which samples the Brillouin zone using 64 k-points (a 4x4x4 mesh) corresponds to a canonical EOM-CCSD calculation of 768 electrons in 640 orbitals. We study eight simple semiconductors and insulators, with direct singlet excitation energies in the range of 3 to 15 eV. Our predicted excitation energies exhibit a mean absolute error of 0.27 eV when compared to experiment. We furthermore calculate the energy of excitons with nonzero momentum and compare the exciton dispersion of LiF with experimental data from inelastic X-ray scattering. By calculating excitation energies under strain, we extract hydrostatic deformation potentials in order to quantify the strength of interactions between excitons and acoustic phonons. Our results indicate that coupled-cluster theory is a promising method for the accurate study of a variety of exciton phenomena in solids.
