各向异性系统的计算机模拟研究。十八。圆柱形和球形颗粒致线虫混合物的再入相分离

R. Hashim, G. R. Luckhurst, S. Romano
{"title":"各向异性系统的计算机模拟研究。十八。圆柱形和球形颗粒致线虫混合物的再入相分离","authors":"R. Hashim, G. R. Luckhurst, S. Romano","doi":"10.1098/rspa.1990.0063","DOIUrl":null,"url":null,"abstract":"Addition of a solute composed of quasi-spherical molecules to a nematic liquid crystal is known to depress the nematic–isotropic transition temperature. A biphasic régime, consisting of coexisting nematic and isotropic phases, is also created at the transition. A molecular field theory of such mixtures, developed by Humphries and Luckhurst, predicts, in addition, the appearance of a re-entrant biphasic region following the nematic phase for a narrow range of compositions. This unusual re-entrant phase separation has not been observed for real nematogenic mixtures, presumably because the system freezes before the re-entrant phases can be formed. Here we report the observation of this biphasic régime for a model nematogenic mixture, formed from cylindrical and spherical particles, which was studied using the Monte Carlo technique of computer simulation. The particles are confined to the sites of a simple cubic lattice but still retain their rotational freedom; in consequence the mixture is unable to freeze in the conventional sense. The temperature variation of the heat capacity and the solute–solute radial distribution function reveal the predicted transition to the re-entrant biphasic régime. The internal energy and the second-rank orientational order parameter were also determined as a function of temperature. The predictions of the Humphries–Luckhurst theory are found to be in good qualitative accord with the results of the simulation.","PeriodicalId":20605,"journal":{"name":"Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1990-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"8","resultStr":"{\"title\":\"Computer simulation studies of anisotropic systems. XVIII. Re-entrant phase separation in nematogenic mixtures of cylindrical and spherical particles\",\"authors\":\"R. Hashim, G. R. Luckhurst, S. Romano\",\"doi\":\"10.1098/rspa.1990.0063\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Addition of a solute composed of quasi-spherical molecules to a nematic liquid crystal is known to depress the nematic–isotropic transition temperature. A biphasic régime, consisting of coexisting nematic and isotropic phases, is also created at the transition. A molecular field theory of such mixtures, developed by Humphries and Luckhurst, predicts, in addition, the appearance of a re-entrant biphasic region following the nematic phase for a narrow range of compositions. This unusual re-entrant phase separation has not been observed for real nematogenic mixtures, presumably because the system freezes before the re-entrant phases can be formed. Here we report the observation of this biphasic régime for a model nematogenic mixture, formed from cylindrical and spherical particles, which was studied using the Monte Carlo technique of computer simulation. The particles are confined to the sites of a simple cubic lattice but still retain their rotational freedom; in consequence the mixture is unable to freeze in the conventional sense. The temperature variation of the heat capacity and the solute–solute radial distribution function reveal the predicted transition to the re-entrant biphasic régime. The internal energy and the second-rank orientational order parameter were also determined as a function of temperature. The predictions of the Humphries–Luckhurst theory are found to be in good qualitative accord with the results of the simulation.\",\"PeriodicalId\":20605,\"journal\":{\"name\":\"Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1990-06-08\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"8\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1098/rspa.1990.0063\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1098/rspa.1990.0063","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 8

摘要

在向列相液晶中加入由准球形分子组成的溶质可以降低向列相各向同性转变温度。在过渡阶段还形成了由共存的向列相和各向同性相组成的双相体制。此外,汉弗莱斯和卢克赫斯特提出的这种混合物的分子场理论预测,在一个狭窄的组合物范围内,向列相之后会出现一个重新进入的双相区域。这种不寻常的再入相分离在真正的线虫源混合物中没有观察到,可能是因为系统在再入相形成之前就冻结了。本文报道了用计算机模拟蒙特卡罗技术研究了由圆柱形和球形颗粒形成的模型线虫混合物的双相结构的观察结果。粒子被限制在一个简单的立方晶格的位置,但仍然保持它们的旋转自由;因此,混合物不能在传统意义上冻结。热容的温度变化和溶质-溶质径向分布函数揭示了预测的向再入双相体系的转变。并确定了内能和二级取向参数随温度的变化规律。汉弗莱斯-卢克赫斯特理论的预测结果与模拟结果在定性上是一致的。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
Computer simulation studies of anisotropic systems. XVIII. Re-entrant phase separation in nematogenic mixtures of cylindrical and spherical particles
Addition of a solute composed of quasi-spherical molecules to a nematic liquid crystal is known to depress the nematic–isotropic transition temperature. A biphasic régime, consisting of coexisting nematic and isotropic phases, is also created at the transition. A molecular field theory of such mixtures, developed by Humphries and Luckhurst, predicts, in addition, the appearance of a re-entrant biphasic region following the nematic phase for a narrow range of compositions. This unusual re-entrant phase separation has not been observed for real nematogenic mixtures, presumably because the system freezes before the re-entrant phases can be formed. Here we report the observation of this biphasic régime for a model nematogenic mixture, formed from cylindrical and spherical particles, which was studied using the Monte Carlo technique of computer simulation. The particles are confined to the sites of a simple cubic lattice but still retain their rotational freedom; in consequence the mixture is unable to freeze in the conventional sense. The temperature variation of the heat capacity and the solute–solute radial distribution function reveal the predicted transition to the re-entrant biphasic régime. The internal energy and the second-rank orientational order parameter were also determined as a function of temperature. The predictions of the Humphries–Luckhurst theory are found to be in good qualitative accord with the results of the simulation.
求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
自引率
0.00%
发文量
0
期刊最新文献
Some examples of Penrose’s quasi-local mass construction The influence of diffusion on the current-voltage curve in a flame ionization detector High strain-rate shear response of polycarbonate and polymethyl methacrylate On the evolution of plane detonations On the solutions of a class of dual integral equations occurring in diffraction problems
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1