An off-lattice kinetic Monte Carlo kernel guided by topological and geometrical analysis to bridge accurate ab-initio calculations and large scale simulations
Résumé
The kMC method is traditionally used on-lattice, where a property such as atomic type, is assigned to each point of a fixed lattice. The evolution is then a series of changes on the property of lattice points, called events given by a catalog, that occur with a probability associated with
reaction barriers.
In the more general case, ie object-kMC1, the concept of event is not restricted to single atom transformations. Due to limitations imposed by the lattice, these approaches often fall short for complex system evolution, such as ion diffusion in amorphous/disordered solids, collective
transformations, or events with specific environmental dependency. In2, to accelerate molecular dynamics through OKMC, off-lattice capabilities have been implemented by using on-the-fly search of events, enabled by graph theory and empirical potential. We propose an alternative approach that uses graph theory and geometric shape-matching to build a catalog from ab-initio results, and take into account the symmetries of events which allows their execution in any direction, without need of lattice. Our proposed atom-resolved off-lattice kMC can treat a large variety of systems. Some examples will be shown emphasizing the different capabilities.