(359h) Coarse-Grained Monte Carlo Simulations of Continuous Systems

Various types of Monte Carlo simulations are used extensively to simulate an enormous range of material properties. Restricting particle positions to fixed lattice sites can substantially increase the computational efficiency of a simulation, and this benefit increases as the lattice becomes coarser. However, the confinement of particle positions to a rigid lattice necessarily reduces the available configurational degrees of freedom in a system and this constraint can become very important at elevated temperatures [1, 2].

In this presentation, we discuss a new framework for performing Metropolis Monte Carlo (MMC) and kinetic Monte Carlo (KMC) simulations of continuous systems on coarse, rigid lattices, while preserving the phase-space contributions of the missing degrees-of-freedom. The present approach relies on the pre-computation of coarse-grained interaction potentials and entropy differences using equilibrium sampling of small systems. We consider simple pair interaction potentials as inputs into the coarse-graining procedure [3]. The resulting coarse interaction potentials are generated in such a way so as to be scalable to different temperatures without the need for a new set of calculations for each temperature. The coarse-grained simulation methodologies are shown to reproduce both equilibrium (e.g. phase diagram), and non-equilibrium (e.g. aggregation dynamics) features in the corresponding fully resolved systems. In the latter case, the coarse potential is used to compute rates that are appropriate for moves in a coarse-grained KMC system.

[1] S. S. Kapur, M. Prasad, J. C. Crocker, T. Sinno, Role of configurational entropy in the thermodynamics of clusters of point defects in crystalline solids, Phys. Rev. B 72, 014119 (2005). [2] J. Dai, W. D. Seider and T. Sinno, Lattice kinetic Monte Carlo simulations of defect evolution in crystals at elevated temperature. Molecular Simulation, 32, 305 (2006). [3] C.F. Tejero, A. Daanoun, H.N.W. Lekkerkerker, and M. Baus, Phase diagrams of simple fluids with extreme pair potentials, Phys. Rev. Lett. 73 752 (1994).