Image charge computer simulation

Fig. 2. (a) Periodic images surrounding the simulation box. Interactions are computed with respect to the nearest image which is indicated by the circle, (b) Violation of the minimum image convention resulting from the interaction of QM particle with point charge 1. 

The MI image has been chosen over the Ewald method, because for the system sizes studied the MI method is faster than the Ewald method. Even so, the MI method is slow compared to neutral system simulations. The main obstacle with charged systems is poor scaling with the number of particles. Since all particle pairs interact the computation time scales as N for the MI method. (For large enough N the Ewald method changes from scaling as N to Thus for even rather small system sizes the... 

The simplest simulated system is a Stockmayer fluid structureless particles characterized by dipole-dipole and Leimard-Jones interactions, moving in a box (size L) with periodic boundary conditions. The results described below were obtained using 400 such particles and in addition a solute atom A which can become an ion of charge q embedded in this solvent. The long range nature of the electrostatic interactions is handled within the effective dielectric environment scheme. In this approach the simulated system is taken to be surrounded by a continuum dielectric environment whose relative permittivity (dielectric constant) e is to be chosen self-consistently with that computed from the simulatioa Accordingly, the electrostatic potential between any two particles is supplemented by the image interaction associated with a spherical dielectric boundary of radius (taken equal... 

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