Electronic Excitations of Open Shell Systems in the Grand Canonical and Canonical Time‐Dependent Hartree‐Fock Models. Applications on Hydrocarbon Radical Ions

1972 ◽  
Vol 57 (11) ◽  
pp. 4884-4892 ◽  
Author(s):  
Poul Jo/rgensen
Keyword(s):  
Open Shell ◽  
Time Dependent ◽  
Electronic Excitations ◽  
Hydrocarbon Radical ◽  
Radical Ions ◽  
Hartree Fock ◽  
Grand Canonical

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.

Analytic energy gradients for open-shell coupled-cluster singles and doubles (CCSD) calculations using restricted open-shell Hartree—Fock (ROHF) reference functions

1991 ◽  
Vol 182 (3-4) ◽  
pp. 207-215 ◽  
Author(s):  
Jürgen Gauss ◽  
Walter J. Lauderdale ◽  
John F. Stanton ◽  
John D. Watts ◽  
Rodney J. Bartlett
Keyword(s):  
Open Shell ◽  
Coupled Cluster ◽  
Hartree Fock ◽  
Reference Functions
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