Abstract
We present the development of the method for the refitting the ReaxFF parameters for a system consisting of the mixed transition metal oxides. We have tested several methods allowing to calculate the differences between the vectors of the forces acting on atoms obtained from the reference DFT simulation and the parameters-dependent ReaxFF. We conclude that the footrule method yields the best parameters among the investigated options. We then validate the parameters using the system consisting of the hematite supported (TiO2)n clusters. The results indicate the refitted parameters allow to obtain acceptable geometries of the clusters upon MD simulation on the ReaxFF level, and despite the short timescale lead to the stable structures.
Highlights
Bridging the gaps between different scales is one of the most important challenges in simulations of chemical reactivity
Practicality limits the simulations to relatively small systems, which can be handled by the electronic structure methods—such as Density Functional Theory
The main idea behind the force matching procedure presented in this work is based on the island model, which consists of multiple local optimizing procedures and once in a while exchanging the results between each island [22]
Summary
Among the currently available solutions for this issue, two are the most widely applied—Density Functional based Tight Binding [4,5,6] and ReaxFF [1, 7]. Both these methods rely on the parametrization, but the parameters are used in a different way. ReaxFF takes a different approach, in which an extensive set of parameters and a complex energy expression is used to evaluate the bond orders between the atoms. Several methods have been investigated [9], including Monte Carlo–based simulated annealing algorithm [10, 11], genetic algorithms [12,13,14,15], covariance
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