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RMSD_PP_TS.pdf (1.95 MB)

Fast and Automatic Estimation of Transition State Structures Using Tight Binding Quantum Chemical Calculations

preprint
submitted on 02.07.2020 and posted on 03.07.2020 by Maria Harris Rasmussen, Jan H. Jensen
We present a method for the automatic determination of transition states (TSs) that is based on Grimme’s RMSD-PP semiempirical tight binding reaction path method (J. Chem. Theory Comput. 2019, 15, 2847-2862), where the maximum energy structure along the path serves as an initial guess for DFT TS searches. The method is tested on 100 elementary reactions and located a total of 89 TSs correctly. Of the 11 remaining reactions, nine are shown not to be elementary reaction after all and for one of the two true failures the problem is shown to be the semiempirical tight binding model itself. Furthermore, we show that the RMSD-PP barrier is a good approximation for the corresponding DFT barrier for reactions with DFT barrier heights up to about 30 kcal/mol. Thus, RMSD-PP barrier heights, which can be estimated at the cost of a single energy minimisation, can be used to quickly identify reactions with low barriers, although it will also produce some false positives.

Funding

MHR is supported by a research grant (00022896) from VILLUM FONDEN

History

Email Address of Submitting Author

jhjensen@chem.ku.dk

Institution

University of Copenhagen

Country

Denmark

ORCID For Submitting Author

0000-0002-1465-1010

Declaration of Conflict of Interest

No conflict of interest

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