Tiger Team: tt-vasp-vtst
Variational transition state theory with VASP
The activation energy is elementary information to understand the kinetics of rate limiting events. Variational transition state theory (VTST) is a numerical technique to determine the reaction path and corresponding activation barrier on multidimensional potential energy surface (PES). In practice, discrete interstitial atomic configurations simulate a reaction path which connects two predetermined local minima. The overall performance of the computational search depends on the quality of the projected force along the reaction path in the approach. Within our knowledge, the best performing and the most efficient VTST method is the nudged elastic band (NEB) method, as implemented by Henkelman and Jonsson .
In our research group, the NEB method is one of the mostly employed numerical technique. We will present three applications of the NEB method as following. We have studied the dendrite growth on metallic battery electrodes , which causes a short circuit and battery fire. Our study identified descriptor of the dendrite growth, so-called step crossing barrier, which will be useful for future battery researches. We have explored the charging and discharging mechanism of emerging battery materials , which allows us to screen candidate materials for new cathode design. We have studied the diffusion of a reaction intermediate on the crowded catalyst surface . We have identified the microscopic details of surprisingly rapid motion of a reaction intermediate helped by the fluctuating nature of adatom layer. Since this diffusion occurs beyond experimental resolution, the computational contributions were crucial to explain the rapid motion of reaction intermediate on the crowded surface.
The original implementation in VASP has been extended by applying the patches provided by Henkelmann and Jonsson . Those patches have been combined with several other patches like Wannier90  (tiger team Wannier90@VASP), VASP sol , beef , and the groups own selective DFT-D3 extensions to the Grimme D3 implementation. Due to the fact that some of the patches might alter (shift) results by some fractions of meV, several binaries with different combinations of patches have been provided.
 G. Henkelman and H. Jonsson, J. Chem. Phys. 113, 9978 (2000).
 M. Jäckle, K. Helmbrecht, M. Smits, D. Stottmeister, and A. Groß, Energy Environ. Sci. 11, 3400-3407 (2018).
 H. Euchner, O. Clemens & M. A. Reddy, npj Comput. Mater. 5, Article number: 31 (2019).
 A.-K. Henß, S. Sakong, P. K. Messer, J. Wiechers, R. Schuster, Don C. Lamb, Axel Groß, and Joost Wintterlin, Science 363, 715-718 (2019).
 A. A. Mostofi, J. R. Yates, G. Pizzi, Y. S. Lee, I. Souza, D. Vanderbilt, N. Marzari, Comput. Phys. Commun. 185, 2309 (2014).
 K. Mathew, R. Sundararaman, K. Letchworth-Weaver, T. A. Arias, and R. G. Hennig, J. Chem. Phys. 140, 084106 (2014).
 J. Wellendorff, K. T. Lundgaard, A. Møgelhøj, V. Petzold, D. D. Landis, J. K. Nørskov, T. Bligaard, and K. W. Jacobsen, Phys. Rev. B 85, 235149 (2012).
 S. Grimme, J. Antony, S. Ehrlich, and H. Krieg, J. Chem. Phys. 132, 154104 (2010).
Members of the Tiger-Team:
Institut für Theoretische Chemie, Universität Ulm;
HPC-Kompetenzzentrum für computergestützte Chemie und Quantenwissenschaften, Universität Ulm