Long-range forces and data compression in Vortex State simulations

Fangohr, Hans, Cox, Simon, Price, Andrew, Daniell, Geoffrey J., Robinson, Alexa M. and de Groot, P.A.J. (2000) Long-range forces and data compression in Vortex State simulations.

Abstract

We report on two aspects of simulations of the vortex state in high-temperature superconductors. Firstly, we cover the treatment of the involved long-range forces. Secondly, we suggest improvements on how to compress vortex position data effectively to enable visualisation of complex systems. A number of problems arise when long-range forces such as $K_1(x)$ or $1/x$ are used in particle-particle simulations. If a simple cut-off for the interaction is used, the system may find an equilibrium configuration at zero temperature that is not a regular lattice yet has an energy lower than the theoretically predicted minimum for the physical system: this is an artefact of the cut-off [1]. We have developed two methods to overcome these problems in Monte Carlo and molecular dynamics simulations. The first uses a smoothed potential to truncate the interaction in a single unit cell: this is appropriate for phenomenological characterisations, but may be applied to any potential. The second is a new method for the $K_0(x)$ potential and sums the energy in an infinitely tiled periodic system, which is in excess of 20,000 times faster than previous naive methods which add periodic images in shells of increasing radius: this is suitable for quantitative studies. Finally, we demonstrate how tree methods and space filling curves can be used to store particle data more efficiently. [1] H. Fangohr et. al., Peter A.J. de Groot and Geoffrey J. Daniell and Ken S. Thomas (2000) Efficient Methods for Handling Long-Range Forces in Particle-Particle Simulations. Journal of Computational Physics, 162 p.372-384.

This record has no associated files available for download.

Contributors

Author: Hans Fangohr

Download statistics