Temperature-accelerated dynamics for simulation of infrequent events

Abstract

We present a method for accelerating dynamic simulations of activated processes in solids. By raising the temperature, but allowing only those events that should occur at the original temperature, the time scale of a simulation is extended by orders of magnitude compared to ordinary molecular dynamics, while preserving the correct dynamics at the original temperature. The main assumption behind the method is harmonic transition state theory. Importantly, the method does not require any prior knowledge about the transition mechanisms. As an example, the method is applied to a study of surface diffusion, where concerted processes play a key role. In the example, times of hours are achieved at a temperature of 150 K.

Formation, migration, and clustering of delocalized vacancies and interstitials at a solid-state semicoherent interface

“…Examples of such methods are temperature accelerated dynamics (TAD) 93 , the parallel replica method 94 , activation-relaxation techniques (ART) 95,96 and variants of algorithms where energy basins are filled by introducing artificial potentials, some of which are called metadynamics 97,98 and other hyperdynamics 99,100 .…”

“Bulk” Nanocrystalline Metals: Review of the Current State of the Art and Future Opportunities for Copper and Copper Alloys

“…89,90 Moreover, simulations show that some solute atoms (dopants) can provide additional strengthening for grain boundary related deformation processes and nanocrystalline materials, in general. 29,92 Furthermore, the development of tools and algorithms that extend both the length and time scales of molecular dynamics [93][94][95] as well as the ability to characterize and visualize atomistic results [96][97][98][99][100] can aid in using molecular dynamics as a tool for insight into nanocrystalline materials design and behavior. While these simulations can give atomistic details of the nature of these solute atoms in thermal stability and deformation, there have been a limited number of atomistic studies of binary and higher-order alloys compared to the large amount of literature devoted to pure nanocrystalline copper, in part due to the limited number of appropriate interatomic potentials.…”

Influence of the prefactor to defect motion inα-Iron during long time scale simulations

“…For the vacancy defect we had to increase the temperature to 750 K in order to find transitions using the MD technique due to the time scales of the migration mechanisms and then recalculate simulation times at 450 K by using eq. 8 as in the TAD method [24]:…”