Electronic excitation energies of pyrimidine studied using coupled cluster response theory

2001 ◽  
Vol 3 (5) ◽  
pp. 730-740 ◽  
Author(s):  
Anders Öhrn ◽  
Ove Christiansen
Keyword(s):  
Electronic Excitation ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies

Tensor Hypercontraction Equation-of-Motion Second-Order Approximate Coupled Cluster: Electronic Excitation Energies in O(N4) Time

2013 ◽  
Vol 117 (42) ◽  
pp. 12972-12978 ◽  
Author(s):  
Edward G. Hohenstein ◽  
Sara I. L. Kokkila ◽  
Robert M. Parrish ◽  
Todd J. Martínez
Keyword(s):  
Electronic Excitation ◽  
Equation Of Motion ◽  
Second Order ◽  
Coupled Cluster ◽  
Excitation Energies

scholarly journals Partition of electronic excitation energies: the IQA/EOM-CCSD method

2019 ◽  
Vol 21 (25) ◽  
pp. 13428-13439 ◽  
Author(s):  
Alberto Fernández-Alarcón ◽  
José Luis Casals-Sainz ◽  
José Manuel Guevara-Vela ◽  
Aurora Costales ◽  
Evelio Francisco ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Noncovalent Interactions ◽  
Equation Of Motion ◽  
Electronic Energy ◽  
Molecular Cluster ◽  
Coupled Cluster ◽  
Energy Partition ◽  
Excitation Energies ◽  
Coupled Cluster Theory ◽  
Interacting Quantum Atoms

We put together equation of motion coupled cluster theory and the interacting quantum atoms electronic energy partition to determine how an absorbed photon changes atomic energies as well as covalent and noncovalent interactions within a molecule or molecular cluster.

scholarly journals How to Stay out of Trouble in RIXS Calculations Within Equation-of-Motion Coupled-Cluster Damped Response Theory? Safe Hitchhiking in the Excitation Manifold by Means of Core-Valence Separation

2019 ◽  
Author(s):  
Kaushik Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Response Equation ◽  
Divergent Behavior

<div>We present a novel approach for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework. The approach is based on recasting the sum-over-state expressions for RIXS moments into a compact form by using damped response theory. Damped response formalism allows one to circumvent problems of divergent behavior of the response equation in the resonant regime. However, the convergence of response equations in the X-ray frequency range is often erratic due to the resonant nature of the virtual core-excited states embedded in the valence ionization continuum. We demonstrate that this problematic behavior can be avoided by extending the core-valence separation (CVS) scheme, which decouples the valence-occupied and core-occupied excitation manifolds, into the response domain. The accuracy of the CVS-enabled damped response theory, implemented within the EOM-EE-CCSD (EOM-CC for excitation energies with single and double excitations) framework, is assessed by comparison against damped EOM-EE-CCSD response calculations. The capabilities of the new approach are illustrated by calculations of RIXS cross sections for benzene and benzene radical cation.</div>

scholarly journals How to Stay out of Trouble in RIXS Calculations Within the Equation-of-Motion Coupled-Cluster Damped Response Theory Framework? Safe Hitchhiking in the Excitation Manifold by Means of Core-Valence Separation

2019 ◽  
Author(s):  
Kaushik Nanda ◽  
Marta L. Vidal ◽  
Rasmus Faber ◽  
Sonia Coriani ◽  
Anna Krylov
Keyword(s):  
Cross Sections ◽  
Equation Of Motion ◽  
Coupled Cluster ◽  
Response Theory ◽  
Excitation Energies ◽  
X Ray ◽  
X Ray Scattering ◽  
Novel Approach ◽  
Response Equation ◽  
Divergent Behavior

<div>We present a novel approach for computing resonant inelastic X-ray scattering (RIXS) cross sections within the equation-of-motion coupled-cluster (EOM-CC) framework. The approach is based on recasting the sum-over-state expressions for RIXS moments into a compact form by using damped response theory. Damped response formalism allows one to circumvent problems of divergent behavior of the response equation in the resonant regime. However, the convergence of response equations in the X-ray frequency range is often erratic due to the resonant nature of the virtual core-excited states embedded in the valence ionization continuum. We demonstrate that this problematic behavior can be avoided by extending the core-valence separation (CVS) scheme, which decouples the valence-occupied and core-occupied excitation manifolds, into the response domain. The accuracy of the CVS-enabled damped response theory, implemented within the EOM-EE-CCSD (EOM-CC for excitation energies with single and double excitations) framework, is assessed by comparison against damped EOM-EE-CCSD response calculations. The capabilities of the new approach are illustrated by calculations of RIXS cross sections for benzene and benzene radical cation.</div>

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