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Author Sur, C. ♦ Chaudhuri, R. K.
Source Indian Institute of Astrophysics
Content type Text
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Physics
Subject Keyword Coupled cluster calculations
Description In this Letter, we study the effects of higher body excitations in the relativistic CC calculations for atoms and ions with one valence electron using Fock-space CCSD, CCSD(T) and its unitary variants. The present study demonstrates that CCSD(T) estimates the ionization potentials (IPs) and the valence electron removal energies quite accurately for alkali atoms and singly ionized alkaline earth ions, but yields unphysical energy levels for atoms and/or ions with partially filled sub-shell like C II. We further demonstrate that the higher body excitation effects can be incorporated more effectively through the unitary coupled cluster theory (UCC) compared to the CCSD(T) method.
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Institution Elsevier B.V.
Journal Chemical Physics Letters
Volume Number 442
Issue Number 13
Size (in Bytes) 245.11 kB
Page Count 7
Starting Page 150
Ending Page 156