密度影响二维软芯晶体熔化的相变类型
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- 英文论文题名：Discontinuous to continuous hexatic-liquid transition in two dimensional melting of soft-core systems
- 论文作者：祖梦婕 ; 柳军 ; 童华 ; 徐宁
- 英文论文作者：Mengjie Zu ; Jun Liu ; Hua Tong ; Ning Xu ; CAS Key Laboratory of Soft Matter Chemistry ; Hefei National Laboratory for Physical Sciences at the Microscale ; and Department of Physics ; University of Science and Technology of China
- 年：2016
- 作者机构：中国科学技术大学物理系中科院软物质化学重点实验室合肥微尺度物质科学国家实验室;
- 论文关键词：二维熔化 ; 六角相 ; 软芯颗粒 ; 胶体 ; 相变
- 会议召开时间：2016-08-25
- 会议录名称：中国化学会2016年软物质理论计算与模拟会议论文摘要集
- 语种：中文
- 分类号：O792
- 学会代码：ZGHY
- 会议名称：中国化学会2016年软物质理论计算与模拟会议
- 会议地点：中国天津
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：2
- 文件大小：147k
- 原文格式：D
- 会议级别：全国
摘要
根据KTHNY理论[1-4],二维固体的熔化是个两步过程。在固相和液相之间存在着一个称为六角相的中间相,从固相到六角相和从六角相到液相的相变都是连续相变。近期的研究表明,硬球体系的六角相-液相相变是一级相变[5],而且随着颗粒硬度的减小,六角相-液相相变经历了从非连续到连续的转变[6]。我们研究了赫兹、简谐和高斯核三个典型的软芯颗粒模型体系,这些体系都呈现出可重入结晶(熔化)现象,在密度ρ_m处达到最大熔化温度T_m。有趣的是,ρ_m对应着一个转变。当ρ<ρ_m时,六角相-液相相变呈现出显著的一级相变特性,存在着一个液相和六角相共存的密度区间。这个密度区间随着温度的增大而减小,并且在Tm处趋于零。然而当ρ>ρ_m时,六角相-液相相变变成了连续相变。因此,在存在可重入结晶现象的软芯颗粒体系中,密度是影响六角相-液相相变属性的重要因素[7]。
According to the KTHNY theory [1-4],the melting of a two-dimensional solid is a two-stage process.There exists an intermediate phase called hexatic phase between solid and liquid.Transitions from solid to hexatic and from hexatic to liquid are both continuous.Recently,it has been reported that the hexatic-liquid transition of hard particles isdiscontinuous [5] and the transition can evolve from discontinuous to continuous when the softness of particles is tuned [6].Here we study three typical soft-core model systems,Hertzian,harmonic,and Gaussian-core models.These systems all exhibit reentrant crystallization(melting) with a maximum melting temperature Tm happening at a crossover density ρm.It is interesting that ρm acts as a transition point.Hexatic-liquid transition at ρ<ρ_m exhibits strong first order transition features.There is a density interval in which liquid and hexatic phases coexist.The interval decreases with increasing temperature and tends to vanish at T_m.When ρ>ρ_m,however,the hexatic-liquid transition becomes continuous.Therefore,in soft-core systems with reentrant crystallization,density should affect the nature of the hexatic-liquid transition [7].
According to the KTHNY theory [1-4],the melting of a two-dimensional solid is a two-stage process.There exists an intermediate phase called hexatic phase between solid and liquid.Transitions from solid to hexatic and from hexatic to liquid are both continuous.Recently,it has been reported that the hexatic-liquid transition of hard particles isdiscontinuous [5] and the transition can evolve from discontinuous to continuous when the softness of particles is tuned [6].Here we study three typical soft-core model systems,Hertzian,harmonic,and Gaussian-core models.These systems all exhibit reentrant crystallization(melting) with a maximum melting temperature Tm happening at a crossover density ρm.It is interesting that ρm acts as a transition point.Hexatic-liquid transition at ρ<ρ_m exhibits strong first order transition features.There is a density interval in which liquid and hexatic phases coexist.The interval decreases with increasing temperature and tends to vanish at T_m.When ρ>ρ_m,however,the hexatic-liquid transition becomes continuous.Therefore,in soft-core systems with reentrant crystallization,density should affect the nature of the hexatic-liquid transition [7].
引文
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[6]Kapfer S.C.;Krauth W.Phys.Rev.Lett.2015,114:035702.
[7]Zu M.;Liu J.;Tong H.;Xu N.ar Xiv:1605.00747(submitted).
[2]Nelson D.R.;Halperin B.I.Phys.Rev.B 1979,19:2457.
[3]Halperin B.I.;Nelson D.R.Phys.Rev.Lett.1978,41:121.
[4]Young A.P.Phys.Rev.B 1979,19:1855.
[5]Bernard E.P.;Krauth W.Phys.Rev.Lett.2011,107:155704.
[6]Kapfer S.C.;Krauth W.Phys.Rev.Lett.2015,114:035702.
[7]Zu M.;Liu J.;Tong H.;Xu N.ar Xiv:1605.00747(submitted).