Equation-of-motion coupled-cluster theory based on the 4-component Dirac–Coulomb(–Gaunt) Hamiltonian. Energies for single electron detachment, attachment, and electronically excited states
2018; American Institute of Physics; Volume: 149; Issue: 17 Linguagem: Inglês
10.1063/1.5053846
ISSN1520-9032
AutoresAvijit Shee, Trond Saue, Lucas Visscher, André Severo Pereira Gomes,
Tópico(s)Fullerene Chemistry and Applications
ResumoWe report in this paper an implementation of 4-component relativistic Hamiltonian based Equation-of-Motion Coupled-Cluster with singles and doubles (EOM-CCSD) theory for the calculation of ionization potential (IP), electron affinity (EA) and excitation energy (EE). In this work we utilize previously developed double group symmetry-based generalized tensor contraction scheme, and also extend it in order to carry out tensor contractions involving non-totally symmetric and odd-ranked tensors. Several approximated spin-free and two-component Hamiltonians can also be accessed in this implementation. We have applied this method to the halogen monoxide (XO, X= Cl, Br, I, At, Ts) species, in order to assess the quality of a few other recent EOMCC implementations, where spin-orbit coupling contribution has been approximated in different degree. Besides, we also have studied various excited states of CH$_2$IBr, CH$_2$I$_2$ and I$_2^-$(as well as single electron attachment and detachment electronic states of the same species) where comparison has been made with a closely related multi-reference coupled-cluster method, namely Intermediate Hamiltonian Fock Space Coupled-Cluster singles and doubles (IHFS-CCSD) theory.
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