A SIMPLE MOLECULAR THEORY OF A NEMATIC NEMATIC PHASE-TRANSITION IN HIGHLY POLAR COMPOUNDS
A SIMPLE MOLECULAR THEORY OF A NEMATIC NEMATIC PHASE-TRANSITION IN HIGHLY POLAR COMPOUNDS
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DOI：
10.1080/02678299308026466
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发表时间：
1993-05-01
期刊：
影响因子：
2.2
通讯作者：
MADHUSUDANA, NV
中科院分区：
文献类型：
--
作者：
GOVIND, AS;MADHUSUDANA, NV
我们已经扩展了一个早期的分子模型，该模型是为了解释高极性化合物中的双重入序列而开发的，以预测在此类化合物中发生双（N1）-双（N2）相变的可能性。在中等密度下，偶极相互作用将引起极性分子的反平行近邻排列，而在较高密度下，偶极诱导的偶极和链-链分散相互作用引起平行配置。N1-N2跃迁对应于两种物质相对浓度的跳跃。用平均场近似计算了相图。弱的一级相变消失在临界点以上作为一个适当的参数的函数。我们还计算了过渡区周围的比热异常。
We have extended an earlier molecular model which was developed to explain the double reentrant sequence in highly polar compounds to predict the possibility of a nematic (N1)-nematic (N2) phase transition in such compounds. At moderate densities the dipolar interactions would give rise to an antiparallel near neighbour arrangement of the polar molecules while at higher densities, the dipole-induced dipole and chain-chain dispersion interactions give rise to a parallel configuration. The N1-N2 transition corresponds to a jump in the relative concentration of the two species. Using the mean field approximation we have calculated the phase diagram. The weak first order transition disappears above a critical point as a function of an appropriate parameter. We have also calculated the specific heat anomaly around the transition region.