摘要
本文建立了同时具有化学势梯度和温度梯度的非平衡系统,研究非对称双原子分子的输运扩散行为.研究发现,双原子分子在非平衡输运中具有取向效应.浓度梯度与温度梯度使双原子分子在输运中产生的大小原子取向的方向刚好相反,沿着梯度的正方向,前者使小原子在前,后者使大原子在前.通过最小熵产生原理,解释了取向的物理机制.研究结果对于深刻理解非平衡条件下物质的输运与其形态的关系具有理论意义.
Non-equilibrium transport is an important research area in statistical physics. The influences of the structures of polyatomic molecules on their transport have attracted the attention of researchers. Up to now, most of researchers deemed that temperature gradient is the main factor for molecular orientation and neglected the effect of the chemical potential gradient on the molecular orientation. To make up the deficiency in the study of chemical potential gradients,we build a non-equilibrium system with both chemical potential gradient and temperature gradient, and study the transport diffusion behavior of asymmetric diatomic molecules by using molecular dynamics and Monte Carlo methods.It is found that the diatomic molecules implement the orientation effect during non-equilibrium transport. Under the chemical potential gradient, the molecular orientation effect leads to the fact that the large atom tends to be in the direction of low concentration particle bath, while the small atom tends to be in the direction of high concentration particle bath. The molecular orientation is opposite to the direction of the flow. Under the temperature gradient, the molecular orientation effect leads to the fact that the large atom tends to be in the direction of high temperature particle bath, while the small atom tends to be in the direction of low temperature particle bath. The molecular orientation is the same as the direction of the flow. The orientation direction caused by concentration gradients is opposite to that caused by temperature gradients and it appears as a competitive relationship. At the same time, the influence of the asymmetry of the molecule itself on the molecular orientation is also studied. The larger the asymmetry of the molecule itself（σB/σA）, the more obvious the molecular orientation effect is. When σB/σA 〉1.6, the influence of the asymmetry of the molecule itself on the orientation effect is gradually saturated. When σB/σA = 1, which is also for a symmetric molecule, even if neither the temperature gradient nor the chemical potential gradient is zero, no molecular orientation occurs. We explain the physical mechanism of orientation through the principle of minimum entropy production. This work is of theoretical significance for in depth understanding the relationship between mass transport and molecular structure under non-equilibrium conditions.
作者
江智亮
陈沛荣
钟伟荣
艾保全
邵志刚
Jiang Zhi-Liang;Chen Pei-Rong;Zhong Wei-Rong;Ai Bao-Quan;Shao Zhi-Gang(Department of Physics and Siyuan Laboratory,Jinan University,Guangzhou 510632,China;Guangdong Province Key Laboratory of Quantum Engineering and Quantum Materials,School of Physics and Telecommunication Engineering,South China Normal University,Guangzhou 510006,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第22期371-375,共5页
Acta Physica Sinica
基金
国家自然科学基金(批准号：11575064)
广东省自然科学基金(批准号：2014A030313367)资助的课题
关键词
双原子分子
输运扩散
取向效应
熵产生率
diatomic molecules
transport diffusion
orientation effect
entropy production rate
