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Triple and quadruple excitation contributions to the binding in Be clusters: Calibration calculations on Be3

Technical Report ·
OSTI ID:5900276
The contribution of connected triple and quadruple excitations to the binding in Be3 is investigated by comparing various coupled-cluster (CC) and truncated configuration interaction (CI) treatments with multireference CI (MRCI) and full CI(FCI) calculations. The CC method with single and double excitations (CCSD) produces results that differ substantially from more elaborate treatments, but most extensions to CCSD that account approximately for connected triple excitations perform very well. In constrast, good agreement with FCI for Be2 can be achieved only with the highest level CC and MRCI methods.
Research Organization:
National Aeronautics and Space Administration, Moffett Field, CA (USA). Ames Research Center
OSTI ID:
5900276
Report Number(s):
N-91-16728; NASA-TM--103391; NAS--1.15:103391; CNN: NCC2-371
Country of Publication:
United States
Language:
English