Simulation studies of dipole correlation in the isotropic liquid phase

被引:24
作者
Cook, MJ [1 ]
Wilson, MR [1 ]
机构
[1] Univ Durham, Dept Chem, Durham DH1 3LE, England
关键词
D O I
10.1080/026782900750037149
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The Kirkwood correlation factor g(1) determines the preference for local parallel or antiparallel dipole association in the isotropic phase. Calamitic mesogens with longitudinal dipole moments and Kirkwood factors greater than 1 have an enhanced effective dipole moment along the molecular long axis. This leads to higher values of Delta epsilon in the nematic phase. This paper describes state-of-the-art molecular dynamics simulations of two calamitic mesogens 4-(trans-4-n-pentylcyclohexyl)benzonitrile (PCH5) and 4-(trans-4-n-pentylcyclohexyl) chlorobenzene (PCH5-Cl) in the isotropic liquid phase using an all-atom force field and taking long range electrostatics into account using an Ewald summation. Using this methodology, PCH5 is seen to prefer antiparallel dipole alignment with a negative g(1) and PCH5-Cl is seen to prefer parallel dipole alignment with a positive g(1); this is in accordance with experimental dielectric measurements. Analysis of the molecular dynamics trajectories allows an assessment of why these molecules behave differently.
引用
收藏
页码:1573 / 1583
页数:11
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