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Keld L. Bak

The accurate determination of molecular equilibrium structures

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Equilibrium structures have been determined for 19 molecules using least-squares fits involving rotational constants from experiment and vibrational corrections from high-level electronic-structure calculations. Equilibrium structures obtained by this procedure have a uniformly high quality. Indeed, the accuracy of the results reported here likely surpasses that reported in most experimental determinations. In addition, the accuracy of equilibrium structures obtained by energy minimization has been calibrated for the following standard models of ab initio theory: Hartree-Fock, MP2, CCSD, and CCSD(T). In accordance with previous observations, CCSD(T) is significantly more accurate than the other models; the mean and maximum absolute errors for bond distances of the 19 molecules are 0.09 and 0.59 pm, respectively, in CCSD(T)/cc-pCVQZ calculations. The maximum error is obtained for R(OO) in H(2)O(2) and is so large compared with the mean absolute error that an experimental reinvestigation of this molecule is warranted. (C) 2001 American Institute of Physics.

Original languageEnglish
JournalJournal of Chemical Physics
Volume114
Issue15
Pages (from-to)6548-6556
Number of pages9
ISSN0021-9606
Publication statusPublished - 15 Apr 2001

    Research areas

  • ANHARMONIC-FORCE FIELD, GAUSSIAN-BASIS SETS, 2ND DERIVATIVES, WAVE-FUNCTIONS, ETHYLENE, METHANE, STATE, BORON, NEON

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