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Quantum mechanical calculations to chemical accuracyThe accuracy of current molecular-structure calculations is illustrated with examples of quantum mechanical solutions for chemical problems. Two approaches are considered: (1) the coupled-cluster singles and doubles (CCSD) with a perturbational estimate of the contribution of connected triple excitations, or CCDS(T); and (2) the multireference configuration-interaction (MRCI) approach to the correlation problem. The MRCI approach gains greater applicability by means of size-extensive modifications such as the averaged-coupled pair functional approach. The examples of solutions to chemical problems include those for C-H bond energies, the vibrational frequencies of O3, identifying the ground state of Al2 and Si2, and the Lewis-Rayleigh afterglow and the Hermann IR system of N2. Accurate molecular-wave functions can be derived from a combination of basis-set saturation studies and full configuration-interaction calculations.
Document ID
19920027668
Document Type
Reprint (Version printed in journal)
Authors
Bauschlicher, Charles W., Jr. (NASA Ames Research Center Moffett Field, CA, United States)
Langhoff, Stephen R. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 15, 2013
Publication Date
October 18, 1991
Publication Information
Publication: Science
Volume: 254
ISSN: 0036-8075
Subject Category
CHEMISTRY AND MATERIALS (GENERAL)
Distribution Limits
Public
Copyright
Other