关键词: 双原子分子/
输运扩散/
取向效应/
熵产生率
English Abstract
Orientation effect of asymmetric diatomic molecules in transport diffusion
Jiang Zhi-Liang1,Chen Pei-Rong1,
Zhong Wei-Rong1,
Ai Bao-Quan2,
Shao Zhi-Gang2
1.Department of Physics and Siyuan Laboratory, Jinan University, Guangzhou 510632, China;
2.Guangdong Province Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 11575064) and the Natural Science Foundation of Guangdong Province, China (Grant No. 2014A030313367).Received Date:17 July 2018
Accepted Date:29 September 2018
Published Online:20 November 2019
Abstract: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.
Keywords: diatomic molecules/
transport diffusion/
orientation effect/
entropy production rate
