Molecular dynamics structural glasses

Chelli, R. Cardini, G. Procacci, P Righini, R. Califano, S. Molecular dynamics of glass-forming liquids structure and dynamics of liquid metatoluidine, J. Chem. Phys. 2002,116, 6205-6215. 

Figure 13 A modified Angell plot of the rescaled fragility displaying the dependence of the structural relaxation times to the scaling quantity r = f I/" for some typical van der Waals liquids and polymers. From Floudas, G. Paluch, M. Grzybowski, A. Ngai, K.L. Molecular Dynamics of Glass-Forming Systems Effects of Pressure Springer Heidelberg, 2011. ...

Various types of power law relaxation have been observed experimentally or predicted from models of molecular motion. Each of them is defined in its specific time window and for specific molecular structure and composition. Examples are dynamically induced glass transition [90,161], phase separated block copolymers [162,163], polymer melts with highly entangled linear molecules of uniform length [61,62], and many others. A comprehensive review on power law relaxation has been recently given by Winter [164],... 

Numerical Simulation of Structural Glasses Comparing Parallel Tempering and Conventional Molecular Dynamics. 

Fig. 4.1 a Typical time evolution of a given correlation function in a glass-forming system for different temperatures (T >T2>...>T ), b Molecular dynamics simulation results [105] for the time decay of different correlation functions in polyisoprene at 363 K normalized dynamic structure factor at the first static structure factor maximum solid thick line)y intermediate incoherent scattering function of the hydrogens solid thin line), dipole-dipole correlation function dashed line) and second order orientational correlation function of three different C-H bonds measurable by NMR dashed-dotted lines)... 

Soules, T. F. (1979). A molecular dynamic calculation of the structure of sodium silicate glasses. J. Chem. Phys. 71, 4570-78. 

Our conclusion is that it is the lack of structure (or spatial order) of the cluster that is the cause of the rapid thermaJization. In aJl our molecular dynamic simulations, the clusters are glass-like and therefore no spatial order exist. The implication is that a perfectly ordered array of hard spheres will not relax. If a perfect crystal of hard spheres at 0 K is directed towards a rigid surface in such a manner that all the atoms of the front face hit the siurface at exactly the same instant then there is no energy dissipation. The cluster rebounds from the inert siurface as if it is rigid, see Fig. 25. 

S. Ispas, M. Benoit, P. Jund, and R. Jullien (2001) Structural and electronic properties of the sodium tetrasilicate glass Na2Si40g from classical and ab initio molecular dynamics simulations. Phys. Rev. B 64, p. 214206... 

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