Cifelli Mario, Cinacchi Giorgio, De Gaetani Luca
Dipartimento di Chimica, Università di Pisa, Via Risorgimento 35, I-56126 Pisa, Italy.
J Chem Phys. 2006 Oct 28;125(16):164912. doi: 10.1063/1.2359428.
Microcanonical molecular dynamics simulations have been performed in the smectic A phase of an elementary liquid-crystal model. Smectic order parameters and diffusion coefficients along directions parallel and perpendicular to the director have been calculated during the same trajectory for a number of state points. This has permitted the satisfactory testing of a procedure, adopted in the analysis of experimental self-diffusion coefficients, leading to an estimate of the temperature dependence of the smectic order parameters. This methodology has been then confidently applied to two smectogenic thermotropic liquid crystals belonging to the 4,4(')-di-n-alkyl-azoxybenzene series. The derived smectic order parameters are larger for the homologue compound with the longest alkyl chains. This is consistent with the well-established increased tendency, for members of a homologue series, to form a smectic phase as their alkyl chains become longer.
在一个基本液晶模型的近晶A相中进行了微正则分子动力学模拟。对于多个状态点，在同一轨迹上计算了近晶序参数以及沿平行和垂直于指向矢方向的扩散系数。这使得对一种用于分析实验自扩散系数的程序进行了令人满意的测试，该程序可用于估计近晶序参数的温度依赖性。然后，该方法被可靠地应用于两种属于4,4'-二正烷基氧化偶氮苯系列的致近晶热致液晶。对于具有最长烷基链的同系物化合物，导出的近晶序参数更大。这与同系物系列成员随着烷基链变长而形成近晶相的趋势增加这一既定现象是一致的。
