In order to understand the long-standing problem of the nature of glass states, we perform intensive simulations on the thermodynamic properties and potential energy surface of an ideal glass. It is found that the ato...In order to understand the long-standing problem of the nature of glass states, we perform intensive simulations on the thermodynamic properties and potential energy surface of an ideal glass. It is found that the atoms of an ideal glass manifest cooperative diffusion, and show clearly different behavior from the liquid state. By determining the potential energy surface, we demonstrate that the glass state has a fiat potential landscape, which is the critical intrinsic feature of ideal glasses. When this potential region is accessible through any thermal or kinetic process, the glass state can be formed and a glass transition will occur, regardless of any special structural character. With this picture, the glass transition can be interpreted by the emergence of conlgurational entropies, as a consequence of flat potential landscapes.展开更多
Molecular dynamics simulations have been performed to investigate the structures of Lennard-Jones （LJ） nanowires （NWs） encapsulated in carbon nanotubes （CNTs）. We find that the structures of NWs in a small CNT o...Molecular dynamics simulations have been performed to investigate the structures of Lennard-Jones （LJ） nanowires （NWs） encapsulated in carbon nanotubes （CNTs）. We find that the structures of NWs in a small CNT only adopt multi-shell motifs, while the structures of NWs in a larger CNT tend to adopt various motifs. Among these structures, three of them have not been reported previously. The phase boundaries among these structures are obtained regarding filling fractions, as well as the interaction between NWs and CNTs.展开更多
Using molecular dynamics simulations,we study the wetting of liquid iron in a carbon nanotube and on a graphene sheet.It is found that the contact angle of a droplet in a carbon nanotube increases linearly with the in...Using molecular dynamics simulations,we study the wetting of liquid iron in a carbon nanotube and on a graphene sheet.It is found that the contact angle of a droplet in a carbon nanotube increases linearly with the increase of wall curvature but is independent of the length of the filled liquid.The contact angle for a droplet on a graphene sheet decreases with the increasing droplet size.The line tension of a droplet on a graphene sheet is also obtained.Detailed studies show that liquid iron near the carbon walls exhibits the ordering tendencies in both the normal and tangential directions.展开更多
Constant-pressure molecular dynamics simulation and the pair analysis technique have been performed to study the microstructural evolution of aluminium during rapid solidification.The microstructure characteristics of...Constant-pressure molecular dynamics simulation and the pair analysis technique have been performed to study the microstructural evolution of aluminium during rapid solidification.The microstructure characteristics of icosahedral ordering increase with decrease of the cooling rate,whereas the microstructure unit characteristics of hep crystalline structure decrease.There are two kinds of microstructure units which are similar to those in the fee crystal containing interstitialcies.These two kinds of microscopic units are nearly independent of the cooling rate.The microscopic structural unit characteristics of fee crystalline structure do not depend on the cooling rate either.These results may help us understand the microstructure of glass and its stability.展开更多
基金Supported by the National Natural Science Foundation of Chinathe National Basic Research Program of China
文摘In order to understand the long-standing problem of the nature of glass states, we perform intensive simulations on the thermodynamic properties and potential energy surface of an ideal glass. It is found that the atoms of an ideal glass manifest cooperative diffusion, and show clearly different behavior from the liquid state. By determining the potential energy surface, we demonstrate that the glass state has a fiat potential landscape, which is the critical intrinsic feature of ideal glasses. When this potential region is accessible through any thermal or kinetic process, the glass state can be formed and a glass transition will occur, regardless of any special structural character. With this picture, the glass transition can be interpreted by the emergence of conlgurational entropies, as a consequence of flat potential landscapes.
基金Project supported by the National Natural Science Foundation of China （Grant No. 11174079）, the National Basic Research Program of China （Grant No. 2012CB921401）, and the Shuguang and Innovation Program of Shanghai Education Committee, China.
文摘Molecular dynamics simulations have been performed to investigate the structures of Lennard-Jones （LJ） nanowires （NWs） encapsulated in carbon nanotubes （CNTs）. We find that the structures of NWs in a small CNT only adopt multi-shell motifs, while the structures of NWs in a larger CNT tend to adopt various motifs. Among these structures, three of them have not been reported previously. The phase boundaries among these structures are obtained regarding filling fractions, as well as the interaction between NWs and CNTs.
基金Supported by the Shuguang and Innovation Project of Shanghai Education Committee and the Basic Research of Shanghai Municipal Science and Technology Commission.
文摘Using molecular dynamics simulations,we study the wetting of liquid iron in a carbon nanotube and on a graphene sheet.It is found that the contact angle of a droplet in a carbon nanotube increases linearly with the increase of wall curvature but is independent of the length of the filled liquid.The contact angle for a droplet on a graphene sheet decreases with the increasing droplet size.The line tension of a droplet on a graphene sheet is also obtained.Detailed studies show that liquid iron near the carbon walls exhibits the ordering tendencies in both the normal and tangential directions.
基金Supported by the National Natural Science Foundation of China under Grant No.19874067the Foundation of the Chinese Academy of Sciences(Grant No.KJ952-J1-412).
文摘Constant-pressure molecular dynamics simulation and the pair analysis technique have been performed to study the microstructural evolution of aluminium during rapid solidification.The microstructure characteristics of icosahedral ordering increase with decrease of the cooling rate,whereas the microstructure unit characteristics of hep crystalline structure decrease.There are two kinds of microstructure units which are similar to those in the fee crystal containing interstitialcies.These two kinds of microscopic units are nearly independent of the cooling rate.The microscopic structural unit characteristics of fee crystalline structure do not depend on the cooling rate either.These results may help us understand the microstructure of glass and its stability.
