• Effect of three-body transformed Hamiltonian $(\tilde{H}_{3})$ using full connected triple excitation coupled cluster operators on valence ionisation potentials of $\rm{Cl_{2}}$ and $\rm{F_{2}}$ computed via $\rm{EIP-VUMRCCSD\tau$ scheme

• Fulltext

https://www.ias.ac.in/article/fulltext/pram/090/03/0036

• Keywords

Triple excitation; transformed Hamiltonian; ionisation potential

• Abstract

Valence universal multireference coupled cluster (VUMRCC) method via eigenvalue independent partitioning has been applied to estimate the effect of three-body transformed Hamiltonian $(\tilde{H}_3)$ on ionisation potentials through full connected triple excitations $S^{(1,0)}_{3}$. $(\tilde{H}_3)$ is constructed using CCSDT1-A model of Bartlett $\it{et al}$ for the ground-state calculation. Contribution of transformed Hamiltonian through full connected triples $\tilde{H}_{3}S^{(1,0)}_{3}$ involves huge amount of computational operations that is time-consuming. Investigation on $\rm{Cl_2}$ and $\rm{F_2}$ molecules using cc-pVDZ and cc-pVTZ basis sets shows that the above effect varies from 0.001 eV to around 0.5 eV, suggesting that inclusion of $\tilde{H}_{3}S^{(1,0)}_{3}$ is essential for highly accurate calculations.

• Author Affiliations

1. Department of Physics, M.B.B. College, Agartala 799 004, India

• Pramana – Journal of Physics

Volume 94, 2020
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Posted on July 25, 2019