A one-site polarizable model for liquid chloroform: COS/C

Abstract

A one-site polarizable liquid chloroform model based on the charge-on-spring method is presented. It consists of five van der Waals sites and point charges, with one polarizable center on the carbon atom. The partial charges were adjusted to fit the gas-phase dipole moment of chloroform, and the Lennard–Jones parameters were varied to reproduce the density and the heat of vapourization of liquid chloroform. In this way, a simple polarizable model for liquid chloroform was obtained that correctly describes a variety of its thermodynamic, dynamic and dielectric properties, while the computational costs are only a factor of 2 higher than for a similar non-polarizable chloroform model. The model is simpler than two previously developed polarizable chloroform models, with four or five polarizable sites. The developed COS/C model is expected to show realistic behaviour of chloroform molecules in response to changes in electric field strength or the dielectric environment and should be applicable in simulations of biomolecules in conjunction with the GROMOS biomolecular force field.

Keywords:

• molecular dynamics
• chloroform
• liquid model
• polarizable force field
• charge-on-spring

Acknowledgements

This work was supported financially by the National Center of Competence in Research (NCCR) in Structural Biology and by grant number 200020-121913 of the Swiss National Science Foundation, by grant number 228076 of the European Research Council (ERC), and by grant number IZLCZ2-123884 of the Cooperation Program of Sino–Swiss Science and Technology, which is gratefully acknowledged.