scholarly journals Excited States of Crystalline Point Defects with Multireference Density Matrix Embedding Theory

2021 ◽  
Author(s):  
Abhishek Mitra ◽  
Hung Pham ◽  
Riddhish Pandharkar ◽  
Matthew Hermes ◽  
Laura Gagliardi
Keyword(s):  
Density Matrix ◽  
Excited States ◽  
Open Shell ◽  
Electronic Excitations ◽  
Complete Active Space ◽  
Hartree Fock ◽  
Embedding Theory ◽  
Consistent Field ◽  
Matrix Embedding ◽  
Self Consistent Field

Accurate and affordable methods to characterize the electronic structure of solids are important for targeted materials design. Embedding-based methods provide an appealing balance in the trade-off between cost and accuracy - particularly when studying localized phenomena. Here, we use the density matrix embedding theory (DMET) algorithm to study the electronic excitations in solid-state defects with a restricted open-shell Hartree--Fock (ROHF) bath and multireference impurity solvers, specifically, complete active space self-consistent field (CASSCF) and n-electron valence state second-order perturbation theory (NEVPT2). We apply the method to investigate an oxygen vacancy (OV) on a MgO(100) surface and find absolute deviations within 0.05 eV between DMET using the CASSCF/NEVPT2 solver, denoted as CAS-DMET/NEVPT2-DMET, and the non-embedded CASSCF/NEVPT2 approach. Next, we establish the practicality of DMET by extending it to larger supercells for the OV defect and a neutral silicon-vacancy in diamond where the use of non-embedded CASSCF/NEVPT2 is extremely expensive.

scholarly journals Excited States of Crystalline Point Defects with Multireference Density Matrix Embedding Theory

2021 ◽  
pp. 11688-11694
Author(s):  
Abhishek Mitra ◽  
Hung Q. Pham ◽  
Riddhish Pandharkar ◽  
Matthew R. Hermes ◽  
Laura Gagliardi
Keyword(s):  
Density Matrix ◽  
Excited States ◽  
Point Defects ◽  
Embedding Theory ◽  
Matrix Embedding

Virtual Synthesis and Optoelectronic Properties of Prismatic Artificial Molecules of In-N and Zn-O: Comparative Studies

2006 ◽  
Vol 959 ◽  
Author(s):  
Liudmila A Pozhar ◽  
Gail J Brown ◽  
William C Mitchel
Keyword(s):  
Electronic Properties ◽  
Quantum Confinement ◽  
Optical Transition ◽  
Level Structure ◽  
Open Shell ◽  
Complete Active Space ◽  
Synthesis Conditions ◽  
Hartree Fock ◽  
Self Consistent Field ◽  
Molecular Synthesis

ABSTRACTThe Hartree-Fock (HF), restricted open shell HF (ROHF), configuration interaction (CI), complete active space (ICASCF), and multiconfiguration self-consistent field (MCSCF) methods provide sophisticated fundamental theory-based, computational tools to study structure, composition,chemistry and electronic properties of small artificial molecules composed of semiconductor compound atoms. These tools are used to synthesize virtually several prismatic In-N and Zn-O artificial molecules whose structure is derived from that of the symmetry elements of the respective wurtzite bulk lattices. Applications of spatial constraints to the atomic coordinates allow modeling molecular synthesis in quantum confinement, to obtain pre-designed molecules with tunable electronic properties. Relaxation of these constraints, or optimization, leads to the corresponding molecules synthesized in “vacuum”. The development of computational templates of the studied artificial molecules synthesized in confinement reflects effects of quantum confinement on the electronic level structure, bonding, the direct optical transition energy, and charge and spin density distributions of the molecules. Comparison of the structure and properties of these molecules to those of their vacuum counterparts leads to a conclusion that a small changes in atomic positions in otherwise structurally similar molecules cause a significant change in their electronic properties. Thus, the electronic properties of artificial molecules can be tuned by changing their synthesis conditions that are defined by atomistic details of quantum confinement where the molecules are synthesized.

Sign in / Sign up

Export Citation Format

Share Document