Equation-of-motion coupled cluster method for high spin double electron attachment calculations Musiał, Monika; Lupa, Łukasz; Kucharski, Stanisław A. [Institute of Chemistry, University of Silesia, Szkolna 9, 40-006 Katowice (Poland)] 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBON; ELECTRON ATTACHMENT; EQUATIONS OF MOTION; EXCITED STATES; POTENTIAL ENERGY; SILICON; SPIN; TRIPLETS The new formulation of the equation-of-motion (EOM) coupled cluster (CC) approach applicable to the calculations of the double electron attachment (DEA) states for the high spin components is proposed. The new EOM equations are derived for the high spin triplet and quintet states. In both cases the new equations are easier to solve but the substantial simplification is observed in the case of quintets. Out of 21 diagrammatic terms contributing to the standard DEA-EOM-CCSDT equations for the R{sub 2} and R{sub 3} amplitudes only four terms survive contributing to the R{sub 3} part. The implemented method has been applied to the calculations of the excited states (singlets, triplets, and quintets) energies of the carbon and silicon atoms and potential energy curves for selected states of the Na{sub 2} (triplets) and B{sub 2} (quintets) molecules. United States 2014-03-21 English Journal Article Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA) Medium: X; Size: page(s) 114107-114107.7 https://doi.org/10.1063/1.4868555 [] 11 140 Journal ID: ISSN 0021-9606; CODEN: JCPSA6; TRN: US14A4710074602 USN 2014-07-31 22253408