Abstract

The new ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach has been proposed and shown to be successful in reproducing benchmark calculations and experimental results. ONIOM3, a three-layered version, divides a system into an active part treated at a very high level of ab initio molecular orbital theory like CCSD(T), a semiactive part that includes important electronic contributions and is treated at the HF or MP2 level, and a nonactive part that is handled using force field approaches. The three-layered scheme allows us to study a larger system more accurately than the previously proposed two-layered schemes IMOMO, which can treat a medium size system very accurately, and IMOMM, which can handle a very large system with modest accuracy. This three-layered scheme has been applied to activation barriers for the Diels−Alder reaction of acrolein + isoprene, acrolein + 2-tert-butyl-1,3-butadiene, and ethylene + 1,4-di-tert-butyl-1,3-butadiene. In general, the results for both geometry optimizations and single point energy calculations agree well with benchmark predictions and experimental results. The scheme has also been applied to the transition state for the oxidative addition of H2 to Pt(P(t-Bu)3)2. The activation energy of this 83-atom reaction is predicted to be 14.2 kcal/mol with the ONIOM3(CCSD(T):MP2:MM3) method.

Keywords

ONIOMChemistryIsopreneAb initioBenchmark (surveying)Energy minimizationMolecular orbitalComputational chemistryAcroleinAtom (system on chip)Physical chemistryMoleculeCatalysisOrganic chemistryCopolymer

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1997 The Journal of Chemical Physics 209 citations

Publication Info

Year
1996
Type
article
Volume
100
Issue
50
Pages
19357-19363
Citations
1932
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Closed

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Mats Svensson, Stéphane Humbel, Robert D. J. Froese et al. (1996). ONIOM:  A Multilayered Integrated MO + MM Method for Geometry Optimizations and Single Point Energy Predictions. A Test for Diels−Alder Reactions and Pt(P(<i>t</i>-Bu)<sub>3</sub>)<sub>2</sub> + H<sub>2</sub> Oxidative Addition. The Journal of Physical Chemistry , 100 (50) , 19357-19363. https://doi.org/10.1021/jp962071j

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DOI
10.1021/jp962071j