Performance of Block Correlated Coupled Cluster Method with the CASSCF Reference Function for Carbon–Carbon Bond Breaking in Hydrocarbons

2009 ◽  
pp. 241-255
Author(s):  
Jun Shen ◽  
Tao Fang ◽  
Shuhua Li
Keyword(s):  
Cluster Method ◽  
Coupled Cluster ◽  
Bond Breaking ◽  
Coupled Cluster Method ◽  
Carbon Bond ◽  
Reference Function ◽  
Carbon Carbon Bond

Equation-of-Motion Coupled-Cluster Method with Double Electron-Attaching Operators: Theory, Implementation, and Benchmarks

2020 ◽  
Author(s):  
Sahil Gulania ◽  
Eirik Fadum Kjønstad ◽  
John F. Stanton ◽  
Henrik Koch ◽  
Anna Krylov
Keyword(s):  
Particle Density ◽  
Equation Of Motion ◽  
Wave Functions ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Bond Breaking ◽  
Coupled Cluster Method ◽  
Density Matrices ◽  
Double Electron ◽  
Structure Patterns

<div> <div> <div> <p>We report a production-level implementation of equation-of-motion coupled-cluster method with double electron- attaching EOM operators of 2p and 3p1h types, EOM-DEA-CCSD. This ansatz, suitable for treating electronic structure patterns that can be described as two-electrons-in-many orbitals, represents a useful addition to EOM-CC family of methods. We analyze the performance of EOM-DEA-CCSD for energy differences and molecular properties. By considering reduced quantities, such as state and transition one-particle density matrices, we can compare EOM-DEA- CCSD wave-functions with wave-functions computed by other EOM-CCSD methods. The benchmarks illustrate that EOM-DEA-CCSD capable of treating diradicals, bond-breaking, and some types of conical intersection. </p> </div> </div> </div>

scholarly journals Equation-of-Motion Coupled-Cluster Method with Double Electron-Attaching Operators: Theory, Implementation, and Benchmarks

2020 ◽  
Author(s):  
Sahil Gulania ◽  
Eirik Fadum Kjønstad ◽  
John F. Stanton ◽  
Henrik Koch ◽  
Anna Krylov
Keyword(s):  
Particle Density ◽  
Equation Of Motion ◽  
Wave Functions ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Bond Breaking ◽  
Coupled Cluster Method ◽  
Density Matrices ◽  
Double Electron ◽  
Structure Patterns

<div> <div> <div> <p>We report a production-level implementation of equation-of-motion coupled-cluster method with double electron- attaching EOM operators of 2p and 3p1h types, EOM-DEA-CCSD. This ansatz, suitable for treating electronic structure patterns that can be described as two-electrons-in-many orbitals, represents a useful addition to EOM-CC family of methods. We analyze the performance of EOM-DEA-CCSD for energy differences and molecular properties. By considering reduced quantities, such as state and transition one-particle density matrices, we can compare EOM-DEA- CCSD wave-functions with wave-functions computed by other EOM-CCSD methods. The benchmarks illustrate that EOM-DEA-CCSD capable of treating diradicals, bond-breaking, and some types of conical intersection. </p> </div> </div> </div>

scholarly journals Equation-of-Motion Coupled-Cluster Method with Double Electron-Attaching Operators: Theory, Implementation, and Benchmarks

2020 ◽  
Author(s):  
Sahil Gulania ◽  
Eirik Fadum Kjønstad ◽  
John F. Stanton ◽  
Henrik Koch ◽  
Anna Krylov
Keyword(s):  
Particle Density ◽  
Equation Of Motion ◽  
Wave Functions ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Bond Breaking ◽  
Coupled Cluster Method ◽  
Density Matrices ◽  
Double Electron ◽  
Structure Patterns

<div> <div> <div> <p>We report a production-level implementation of equation-of-motion coupled-cluster method with double electron- attaching EOM operators of 2p and 3p1h types, EOM-DEA-CCSD. This ansatz, suitable for treating electronic structure patterns that can be described as two-electrons-in-many orbitals, represents a useful addition to EOM-CC family of methods. We analyze the performance of EOM-DEA-CCSD for energy differences and molecular properties. By considering reduced quantities, such as state and transition one-particle density matrices, we can compare EOM-DEA- CCSD wave-functions with wave-functions computed by other EOM-CCSD methods. The benchmarks illustrate that EOM-DEA-CCSD capable of treating diradicals, bond-breaking, and some types of conical intersection. </p> </div> </div> </div>

The relativistic coupled-cluster method: transition energies of bismuth and eka-bismuth

1998 ◽  
Vol 94 (1) ◽  
pp. 181-187 ◽  
Author(s):  
EPHRAIM ELIAV ◽  
UZI KALDOR ◽  
YASUYUKI ISHIKAWA
Keyword(s):  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Transition Energies

A Multi-Layer Approach to the Equation of Motion Coupled-Cluster Method for the Electron Affinity

2020 ◽  
Author(s):  
Soumi Haldar ◽  
Achintya Kumar Dutta
Keyword(s):  
Electron Affinity ◽  
Electron Attachment ◽  
Equation Of Motion ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Large Molecules ◽  
Layer Method ◽  
Speed Up ◽  
Attachment Process

We have presented a multi-layer implementation of the equation of motion coupled-cluster method for the electron affinity, based on local and pair natural orbitals. The method gives consistent accuracy for both localized and delocalized anionic states. It results in many fold speedup in computational timing as compared to the canonical and DLPNO based implementation of the EA-EOM-CCSD method. We have also developed an explicit fragment-based approach which can lead to even higher speed-up with little loss in accuracy. The multi-layer method can be used to treat the environmental effect of both bonded and non-bonded nature on the electron attachment process in large molecules.<br>

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