Novel Transcorrelation Inspired by F12 Electronic Structure Theory
Seiichiro Ten-no
Graduate School of System Informatics, Kobe university, Nada-ku, Kobe, Japan
Vendredi 20 Septembre 2024, 11H00
Bibiothèque du LCT, Couloir 12-13, 4ème étage, Campus Pierre et Marie Curie
Computing electronic structures in high accuracy is one of the most significant challenges in quantum chemistry and physics, while the exponential growth of the full configuration interaction (FCI) dimension with the number of correlated electrons hinders the application of wavefunction theory to large molecules. There has been a recent resurgence of interest in transcorrelation (TC), primarily driven by the two objectives: 1) to combine TC with approximate full configuration interaction (FCI) solvers, and 2) to reduce the number of qubits in quantum simulations by downfolding the high-energy contributions of the Hamiltonian. We recently introduced an alternative nonunitary transcorrelation inspired by the F12 ansatz, the projective transcorrelation (pTC) [1]. The similarity-transformed Hamiltonian of pTC is spin-free to fulfill the singlet and triplet cusp conditions. The importance of this feature will be shown using a perturbative analysis of pTC. We demonstrate the excellent performance of pTC by the application to the full coupled-cluster reduction (FCCR), which is a selected coupled-cluster with screenings for the excitation manifold and nonlinear operations [2,3].
_________________________________
References :
[1] S. L. Ten-no, J. Chem. Phys. 2023, 159, 171103.
[2] E. Xu, M. Uejima, and S. L. Ten-no, Phys. Rev. Lett. 2018, 121, 113001.
[3] E. Xu, M. Uejima, and S. L. Ten-no, J. Phys. Chem. Lett. 2020, 11, 9775.