MD simulation of self-diffusion and structure in some n-alkanes over a wide temperature range at high pressures.
Self-diffusion and structural properties of n-alkanes have been studied by molecular dynamics simulation in the temperature range between the melting pressure curve and 600 K at pressures up to 300 MPa. The simulated results of lower n-alkanes are in good agreement with the existing experimental data, and support the reliability of results of the simulations of self-diffusion coefficients obtained at the extreme conditions. We predict the self-diffusion coefficients for methane, ethane, propane and n-butane at the similar reduced temperatures and pressures to draw a comparison between them. Then the correlation between self-diffusion and structural properties are further investigated by calculating the coordination numbers. Moreover, we define four distances and their corresponding relative deviations to characterize the flexibility of long-chain n-alkanes. The simulated results show that the self-diffusion of n-alkane molecules is mainly affected by the close packing, and the flexibility has a strong impact on the self-diffusion of longer n-alkane molecules.
School of Chemistry and Chemical Engineering, Hainan Normal University, Haikou, 571158, People's Republic of China.
Huajie
H
Feng
Wei
W
Gao
Jingjing
J
Nie
Jing
J
Wang
Xiaojuan
X
Chen
Liuping
L
Chen
Xin
X
Liu
Hans-Dietrich
HD
Lüdemann
Zhenfan
Z
Sun