COMPARISON OF LANGEVIN AND MOLECULAR-DYNAMICS SIMULATIONS - EQUILIBRIUM AND DYNAMICS OF ETHYLENE-GLYCOL IN WATER

被引:50
作者
WIDMALM, G [1 ]
PASTOR, RW [1 ]
机构
[1] US FDA,CTR BIOL EVALUAT & RES,BIOPHYS LAB,8800 ROCKVILLE PIKE,BETHESDA,MD 20892
来源
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS | 1992年 / 88卷 / 13期
关键词
D O I
10.1039/ft9928801747
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The results of molecular dynamics (MD) simulations of one ethylene glycol molecule in 259 waters from trajectories totalling 5 ns are compared with those from Langevin dynamics simulations of a single ethylene glycol. It is found that while the trans-gauche equilibrium constant is relatively unperturbed by water, the effective barrier for isomerization is lowered by ca. 1 kT. Once this effect is taken into account, a Langevin model without explicit waters with a collision frequency, gamma, of ca. 50 ps-1 provides a reasonable description of the average isomerization rate. Overall rotation is well fitted with gamma = 75 ps-1, although the fast librational motion present in MD is overdamped in LD. When hydrodynamic interaction is introduced with the Oseen tensor and the above collision frequencies are assumed, 1-2 bound waters are required to reproduce the translational diffusion constant of the glycol obtained in the MD simulations. These results indicate that Langevin dynamics simulations can reproduce some behaviour of polar molecules in aqueous solutions, but might be better carried out including a partial layer of bound water.
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页码:1747 / 1754
页数:8
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