Viscosity and Diffusion Constants Calculation of n-Alkanes by Molecular Dynamics Simulations

Bulletin of the Korean chemical society

Song Hi Lee¹  Taihyun Chang¹ 

关键词: MD simulation;    Viscosity;    Diffusion;    n-Alkanes;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

In this paper we have presented the results for viscosity and self-diffusion constants of model systems for four liquid n-alkanes (C₁₂, C₂₀, C₃₂, and C₄₄) in a canonical ensemble at several temperatures using molecular dynamics (MD) simulations. The small chains of these n-alkanes are clearly ee ²>/6g ²>>1, which leads to the conclusion that the liquid n-alkanes over the whole temperatures considered are far away from the Rouse regime. Calculated viscosity �? and self-diffusion constants D are comparable with experimental results and the temperature dependence of both �? and D is suitably described by the Arrhenius plot. The behavior of both activation energies, E_�? and E_D, with increasing chain length indicates that the activation energies approach asymptotic values as n increases to the higher value, which is experimentally observed. Two calculated monomeric friction constants �? and ユD give a correct qualitative trend: decrease with increasing temperature and increase with increasing chain length n. Comparison of the time auto-correlation functions of the end-toend vector calculated from the Rouse model for n-dodecane (C₁₂) at 273 K and for n-tetratetracontane (C₄₄) at 473 K with those extracted directly from our MD simulations confirms that the short chain n-alkanes considered in this study are far away from the Rouse regime.

【 授权许可】

Unknown