SEMINAR
The State Key Lab of
High Performance Ceramics and Superfine Microstructure
Shanghai Institute of Ceramics, Chinese Academy of Sciences
中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室

 

Nucleation of tetrahedral solids from their melt by molecular dynamics

Speaker：Davide Donadio

　  Max-Planck-Institute for Polymer Research

 

Biography:

Davide Donadio graduated in Physics at the University of Milan (Italy) in 1998 with a thesis on "Numerical simulation of the growth of carbon films by molecular beam deposition". From 1998 to 2002, he attended the graduate school in Materials Science at the University of Milano Bicocca, and in January 2003 he successfully defended his Ph.D thesis on "Photoconductivity and photoelasticity of silica". After the Ph.D. he moved to a group at ETH Zurich, where he initiated a new activity on the simulation of phase transitions and nucleation events. The research activity encompassed the study of polymorphism in silica, poly-amorphism of ice, melting of ice and crystal nucleation in a Lennard-Jones fluid. Before joining MPIP in January 2010, Davide Donadio spent three years in UC Davis as research associate. There he kept working on nucleation phenomena and he started a new research in the field of thermal transport in materials for thermoelctric applications. He is currently involved in the study of polymer-assisted/inhibited crystallization, biomineralization, organic/inorganic interfaces and thermal transport in materials for organic electronics.

联系人：张文清研究员 (2416)

 

 

Nucleation of tetrahedral solids from their melt by molecular dynamics

Speaker：Davide Donadio

　　 Max-Planck-Institute for Polymer Research

 ABSTRACT:

The early stages of crystallization from molten phases remain largely unknown, due to experimental limitations in spatial and temporal resolutions. Computer simulations, when combined with advanced sampling techniques, can provide valuable details about nucleation at the atomistic level.

Here we report on the development of the forward flux sampling method [1] in conjunction with molecular dynamics and its application to the investigation of crystallization of supercooled tetrahedral liquids, such as Silicon and water. This method allows for a direct computation of the nucleation rate and gives access to atomistic details of the nucleation process, including the atomic structure of critical nuclei and lifetime distributions of subcritical nuclei [2].Through these simulations we have been able to establish the influence of free surfaces in the crystallization of liquid silicon, and we have derived a general thermodynamic explanation of surface freezing in the class of tetrahedral systems, with broad implications in materials and atmospheric sciences [3].The same approach is employed to study homogeneous nucleation of hexagonal and/or cubic ice, and the formation of silicon quantum dots in amorphous silica and silicon nitride matrices.

 

[1] R. J. Allen, D. Frenkel, and P. R. T. Wolde, J. Chem. Phys. 124, 024102 (2006)

[2] T.S. Li, D. Donadio and G. Galli, J. Chem. Phys 131, 224519 (2009)

[3] T.S. Li, D. Donadio, L.M. Ghiringhelli and G. Galli, Nat. Mater. 8, 726, (2009)