A molecular dynamics simulation study of dipole correlation in the isotropic phase of the mesogens me5NF and GGP5CI

CookM.R. Wilson, M.J.

Abstract

Molecular dynamics simulations of the molecules me5NF and GGP5Cl have been undertaken to study dipole correlation in the isotropic phase. The simulations use an all-atom force field developed specifically for these molecules, together with a full treatment of the long range electrostatic interactions via an Ewald sum, me5NF exhibits a preference For anti-parallel dipole association as seen through the distance dependent correlation function g(1)(r). However, GGP5Cl shows no marked preference for parallel or anti-parallel dipole association. Both molecules show the presence of distinct parallel and anti- parallel dipole dimers in the liquid phase. For me5NF the dominant molecular pair configurations arise from Favourable quadrupolar interactions between an unsubstituted phenyl ring and a second phenyl ring with fluorine and cyano substituents. In GGP5Cl, which has two fluorinated phenyl rings, molecules in the liquid phase show an intramolecular preference for an anti- parallel arrangement of C-F bond dipoles, which is absent in the gas phase. Kirkwood correlation factors, g(l), have been calculated from the simulations data. For me5NF, the g(l) result is in excellent agreement with existing experimental data. However, the g(l) result For GGP5Cl is in error. It is suggested that this discrepancy arises due to a failure to model correctly the dipole-induced dipole interactions that arise in this molecule.

Citation

CookM.R. Wilson, M. (2001). A molecular dynamics simulation study of dipole correlation in the isotropic phase of the mesogens me5NF and GGP5CI. Molecular Crystals and Liquid Crystals, 357, 127-+

• Journal Article Type: Article
• Publication Date: 2001
• Journal: Molecular Crystals and Liquid Crystals
• Print ISSN: 1542-1406
• Publisher: Taylor and Francis Group
• Peer Reviewed: Peer Reviewed
• Volume: 357
• Pages: 127-+
• Publisher URL: <Go to ISI>://000168788200010