A COMPARISON OF PARTICLE-PARTICLE, PARTICLE-MESH AND EWALD METHODS FOR CALCULATING ELECTROSTATIC INTERACTIONS IN PERIODIC MOLECULAR-SYSTEMS

We compare the Particle-Particle Particle-Mesh (PPPM) and Ewald method s for calculating electrostatic interactions in periodic molecular sys tems. A brief comparison of the theories shows that the methods are ve ry similar differing mainly in the technique which is used to perform the ''k-space'' or mesh calculation. Because the PPPM utilizes the hig hly efficient numerical Fast Fourier Transform (FFT) method it require s significantly less computational effort than the Ewald method and sc ale's almost linearly with system size.