Journal article
W4 theory for computational thermochemistry: In pursuit of confident sub-kJ/mol predictions
Journal of Chemical Physics, Vol.125(14)
Oct/2006
Abstract
In an attempt to improve on our earlier W3 theory [A. D. Boese , J. Chem. Phys. 120, 4129 (2004)] we consider such refinements as more accurate estimates for the contribution of connected quadruple excitations (T-4), inclusion of connected quintuple excitations (T-5), diagonal Born-Oppenheimer corrections (DBOC), and improved basis set extrapolation procedures. Revised experimental data for validation purposes were obtained from the latest version of the Active Thermochemical Tables thermochemical network. The recent CCSDT(Q) method offers a cost-effective way of estimating T-4, but is insufficient by itself if the molecule exhibits some nondynamical correlation. The latter considerably slows down basis set convergence for T-4, and anomalous basis set convergence in highly polar systems makes two-point extrapolation procedures unusable. However, we found that the CCSDTQ-CCSDT(Q) difference converges quite rapidly with the basis set, and that the formula 1.10[CCSDT(Q)/cc-pVTZ+CCSDTQ/cc-pVDZ-CCSDT(Q)/cc-pVDZ] offers a very reliable as well as fairly cost-effective estimate of the basis set limit T-4 contribution. The T-5 contribution converges very rapidly with the basis set, and even a simple double-zeta basis set appears to be adequate. The largest T-5 contribution found in the present work is on the order of 0.5 kcal/mol (for ozone). DBOCs are significant at the 0.1 kcal/mol level in hydride systems. Post-CCSD(T) contributions to the core-valence correlation energy are only significant at that level in systems with severe nondynamical correlation effects. Based on the accumulated experience, a new computational thermochemistry protocol for first- and second-row main-group systems, to be known as W4 theory, is proposed. Its computational cost is not insurmountably higher than that of the earlier W3 theory, while performance is markedly superior. Our W4 atomization energies for a number of key species are in excellent agreement (better than 0.1 kcal/mol on average
Details
- Title
- W4 theory for computational thermochemistry; In pursuit of confident sub-kJ/mol predictions
- Creators
- Amir Karton (null) - The Weizmann Institute of ScienceElena Rabinovich (null) - The Weizmann Institute of ScienceJan M. L. Martin (null) - The Weizmann Institute of ScienceBranko Ruscic (null) - University of Chicago
- Resource Type
- Journal article
- Publication Details
- Journal of Chemical Physics, Vol.125(14); Oct/2006
- Number of pages
- 17
- Language
- English
- DOI
- https://doi.org/10.1063/1.2348881
- Grant note
- Research was supported by the Israel Science Foundation Grant No. 709/05, the Minerva Foundation Munich, Germany, and the Helen and Martin Kimmel Center for Molecular Design. One of the authors J.M.L.M. is the incumbent of the Baroness Thatcher Professorial Chair of Chemistry and a member ad personam of the Lise MeitnerMinerva Center for Computational Quantum Chemistry. The work at Argonne National Laboratory, together with the underlying fundamental thermochemical development of the ATcT approach, was supported by the U.S. Department of Energy, Division of Chemical Sciences, Geosciences, and Biosciences of the Office of Basic Energy Sciences, under Contract No. W-31 109-ENG-38. Development of inherent computer-science aspects of ATcT and the underpinning data management technologies were supported by the U.S. Department of Energy, Division of Mathematical, Information, and Computational Science of the Office of Advanced Scientific Computing Research, under Contract No. W-31-109- ENG-38 Argonne as part of the multiinstitutional Collaboratory for Multi-Scale Chemical Science CMCS, which is a project within the National Collaboratories Program of the U.S. Department of Energy. The authors would like to thank Professor John F. Stanton University of Texas, Austin, Professor Peter R. Taylor Warwick University, Professor Donald G. Truhlar University of Minnesota, and Professor Hans-Joachim Werner University of Stuttgart for helpful discussions and Dr. Mihály Kallay Budapest University of Technology and Economics for early access to a new version of MRCC and kind assistance with the code. The general ATcT development has benefited from the support and effort of numerous past and present CMCS team members. The research presented in this paper is part of ongoing work in the framework of a Task Group of the International Union of Pure and Applied Chemistry on “Selected Free Radicals and Critical Intermediates: Thermodynamic Properties from Theory and Experiment” 2000-013-2-100 and Renewal No. 2003-024-1-100. See Ref. 63 for further details
- Record Identifier
- 993262962703596
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