A QM/MM equation-of-motion coupled-cluster approach for predicting semiconductor color-center structure and emission frequencies

作     者：Lutz, Jesse J. Duan, Xiaofeng F. Burggraf, Larry W. 

作者机构：ORISE fellow residing at Department of Engineering Physics Air Force Institute of Technology Wright-Patterson Air Force Base OH45433 United States Air Force Research Laboratory DoD Supercomputing Resource Center Wright-Patterson Air Force Base OH45433 United States Air Force Institute of Technology Wright-Patterson Air Force Base OH45433 United States 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2017年

核心收录：

主　　题：Ground state 

摘      要：Valence excitation spectra were computed for deep-center silicon-vacancy defects in 3C, 4H, and 6H silicon carbide (SiC) and comparisons were made with literature photoluminescence measurements. Optimizations of nuclear geometries surrounding the defect centers were performed within a Gaussian basis-set framework using many-body perturbation theory or density functional theory (DFT) methods, with computational expenses minimized by a QM/MM technique called SIMOMM. Vertical excitation energies were subsequently obtained by applying excitation-energy, electronattached, and ionized equation-of-motion coupled-cluster (EOMCC) methods, where appropriate, as well as time-dependent (TD) DFT, to small models including only a few atoms adjacent to the defect center. We consider the relative quality of various EOMCC and TD-DFT methods for (i) energy-ordering potential ground states differing incrementally in charge and multiplicity, (ii) accurately reproducing experimentally measured photoluminescence peaks, and (iii) energy-ordering defects of different types occurring within a given polytype. The extensibility of this approach to transition-metal defects is also tested by applying it to silicon-substituted chromium defects in SiC and comparing with measurements. It is demonstrated that, when used in conjunction with SIMOMM-optimized geometries, EOMCC-based methods can provide a reliable prediction of the ground-state charge and multiplicity, while also giving a quantitative description of the photoluminescence spectra, accurate to within 0.1 eV of measurement for all cases considered. Copyright © 2017, The Authors. All rights reserved.