Cut-off radius effect of the isotropic periodic sum method for polar molecules in a bulk water system

Kazuaki Takahashi, Tetsu Narumi, Kenji Yasuoka

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Molecular dynamics simulation has been applied for water to compare the isotropic periodic sum (IPS) method for polar molecules (IPSp) to the normal IPS (IPSn) method and the Ewald sum by evaluating the diffusion coefficient and liquid structure. In our previous study, we have applied the IPSn method for bulk water and found notable deviation of the radial distribution function g(r). In this work, the IPSp gives a good estimation for the potential energy and the self-diffusion coefficient at a cut-off radius, r c, greater than 2.2nm while avoiding the notable deviation of g(r) which appeared in the case of IPSn. The distance-dependent Kirkwood factor G k(r) was also calculated, and the truncation of a long-range interaction of the cut-off-like method (such as cut-off with or without the switch function and the reaction field) shows serious shortcomings for dipole-dipole correlations in bulk water systems. This was observed by comparing the shape to that of the Ewald sum. G k(r) of the cut-off-like method greatly deviates from that of the Ewald sum. However, the discrepancy of G k(r) for IPSp method was found to be much less than that of other typical cut-off-like methods. We conclude that the IPSp method is an adequately accurate technique for estimating transport coefficients and the liquid structure of water in a homogeneous system at long cut-off distances.

Original languageEnglish
Pages (from-to)397-403
Number of pages7
JournalMolecular Simulation
Issue number5
Publication statusPublished - 2012 Apr 1


  • cut-off method
  • long-range interaction
  • molecular dynamics simulation

ASJC Scopus subject areas

  • Chemistry(all)
  • Information Systems
  • Modelling and Simulation
  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics


Dive into the research topics of 'Cut-off radius effect of the isotropic periodic sum method for polar molecules in a bulk water system'. Together they form a unique fingerprint.

Cite this