Hybrid versus global thermostatting in molecular-dynamics simulation of methane-hydrate crystallisation  

作　　者：Niall J.English Mohammad Reza Ghaani 

机构地区：[1]School of Chemical and Bioprocess Engineering, University College Dublin

出　　处：《Chinese Journal of Chemical Engineering》2019年第9期2180-2188,共9页中国化学工程学报（英文版）

基　　金：the Irish Research Council for Government-of-Ireland postdoctoral fellowship, under grant no. GOIPD/2016/365

摘　　要：Molecular-dynamics(MD)simulations have been performed for the growth of a spherical methane-hydrate nano-crystallite,surrounded by a supersaturated water–methane liquid phase,using both a hybrid and globalsystem thermostatting approach.It was found that hybrid thermostatting led to more sluggish growth and the establishment of a radial temperature profile about the spherical hydrate crystallite,in which the growing crystal phase is at a higher temperature than the surrounding liquid phase in the interfacial region,owing to latent-heat dissipation.In addition,Onsager’s-hypothesis fluctuation–dissipation analysis of fluctuations in the number of crystal-state water molecules at the interface shows slower growth.Molecular-dynamics(MD) simulations have been performed for the growth of a spherical methane-hydrate nano-crystallite, surrounded by a supersaturated water–methane liquid phase, using both a hybrid and globalsystem thermostatting approach. It was found that hybrid thermostatting led to more sluggish growth and the establishment of a radial temperature profile about the spherical hydrate crystallite, in which the growing crystal phase is at a higher temperature than the surrounding liquid phase in the interfacial region, owing to latent-heat dissipation. In addition, Onsager’s-hypothesis fluctuation–dissipation analysis of fluctuations in the number of crystal-state water molecules at the interface shows slower growth.

关 键 词：Molecular dynamics CLATHRATE HYDRATES Crystallisation Thermostatting RADIAL temperature profile Fluctuation–dissipation 

分 类 号：TG1[金属学及工艺—金属学]