Unitary Coupled-Cluster Based Self-Consistent Electron Propagator Theory for Electron-Detached and Electron-Attached States: A Quadratic Unitary Coupled-Cluster Singles and Doubles Method and Benchmark Calculations
Benchmark calculations reveal that unitary coupled-cluster methods achieve high accuracy for electron states, indicating significant advancements in quantum chemistry.
Key Points
This research aims to develop a unitary coupled-cluster based electron propagator theory for better describing electron-detached and attached states.
Developed two schemes: IP/EA-UCC3 and IP/EA-qUCCSD.
Implemented within the coupled-cluster singles and doubles framework.
Used perturbative and commutator-based strategies for Hamiltonian truncation.
Evaluated performance using full configuration interaction reference data.
IP-qUCCSD achieved the highest accuracy among methods for one-hole-dominated ionized states.
Mean absolute deviation of 0.19 eV and standard deviation of 0.13 eV reported.
IP-qUCCSD outperformed the higher-order ADC(4) method despite not including triple excitations.
All methods showed comparable accuracy in one-particle-dominated electron attachment calculations.