Accession Number : ADA263422


Title :   Fast Multipole Method in Simulations of Aqueous Systems


Descriptive Note : Technical rept.


Corporate Author : IBM ALMADEN RESEARCH CENTER SAN JOSE CA


Personal Author(s) : Glosli, James N ; Philpott, Michael R


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a263422.pdf


Report Date : 14 Apr 1993


Pagination or Media Count : 14


Abstract : The fast multipole method (fmm) for calculating electric fields developed by Greengard and Rokhlin (J. Comp. Phys. 73, 325(1987)), has been implemented specifically for molecular dynamics simulations of electrochemical problems including boundary conditions associated with metal electrodes. This order N (number of charged particles) algorithm, is known to be computationally much more efficient than direct or Ewald sum methods (order N 2) for systems with as few as one thousand charged particles (equivalent to 300 water molecules). Timings and accuracy estimates with system size N (16 less than or N less than or equal 16000) are given to illustrate the effectiveness and efficiency of the fmm. As an application of fmm we describe it's use with constant temperature molecular dynamics to calculate the dielectric constant of the space water model in bulk at temperatures 298K and 361K. System sizes of 27, 64, 125 and 216 water molecules were considered. Comparison with the Ewald and reaction field methods was made. At 298K the dielectric constant was calculated to be epsilon = 75.5 + or - 5% and at 361K epsilon = 57.3 + or - 4%. Both values compare well with experiment and the reaction field theory simulations.


Descriptors :   *SIMULATION , *ELECTRIC FIELDS , *MOLECULAR PROPERTIES , ALGORITHMS , METALS , TEMPERATURE , MODELS , DYNAMICS , CHARGED PARTICLES , BOUNDARIES , FIELD THEORY , NUMBERS , CONSTANTS , ELECTRODES , PARTICLES , ESTIMATES , MOLECULES , WATER , DIELECTRICS , ACCURACY , EFFICIENCY , ELECTROCHEMISTRY


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electricity and Magnetism


Distribution Statement : APPROVED FOR PUBLIC RELEASE