Molecular dynamics glass-forming liquids

Figure 14 Ratio of the constant volume activation energy (ij) to the enthalpy of activation (Qp) plotted as afunction of the repeat unit volume (polymers) or the molecular volume (glass-forming liquids). In color are the results from the glass-forming liquids. In general, glass-forming liquids have lower values of the dynamic ratio that results from the larger size of these molecules necessary to avoid ciystallization. The line is the result of a linear fit to all data points. From Floudas, G. Mpoukouvalas, K. Papadopoulos, P. J. Chem. Phys. 2006, 124, 074905. ...

Fig. 12. Adam-Gibbs plots of the dielectric relaxation time of 2-methyltetrahydrofuran (2-MTHF) and 3-bromopentane (3-BP) versus (Tsconi) . The lines are VTF fits, 7 fus is the fusion temperature, and Tb is the temperature below which the VTF equation applies. /I ag and Avf are prefactors in the Adam-Gibbs and VTF equations, respectively. Tk is the calorimetri-cally determined Kauzmann temperature, and To is the VTF singular temperature, which were set equal in the VTF (line) fits. (Reprinted with permission from R. Richer and C. A. Angell. Dynamics of glass-forming liquids. V. On the link between molecular dynamics and configurational entropy. J. Chem. Phys. (1998) 108 9016. Copyright 1998, American Institute of Physics.)...

Richert, R., and Angell, C. A., Dynamics of glass-forming liquids. V. On the link between molecular dynamics and configurational entropy. J. Chem. Phys. 108, 9016 (1998). 

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. 

G. Johnson, A. I. Mel cuk, H. Gould, W. Klein, and R. D. Mountain. Molecular-dynamics study of long-lived structures in a fragile glass-forming liquid. Phys. Rev. ,57(1998), 5707-5718. 

Shenhar R, Norsten TB, Rotello VM (2005) Polymer-mediated nanoparticle assembly structural control and applications. Adv Mater 17(6) 657-669 Sinha G, Glorieux C, Thoen J (2004) Broadband dielectric spectroscopy study of molecular dynamics in the glass-forming liquid crystal isopentylcyanobiphenyl dispersed with aerosils. Phys Rev E 69 031707-031712... 

An appealing approach to the study of nucleation is to observe it directly in a computer simulation using the method of molecular dynamics. It is evident that one cannot closely mimic experimental conditions, since computer time scales extend only over tens to hundreds of picoseconds. Thus deep quenches carried out at high quench rates are necessary to form supercooled liquids that have some reasonable chance of nucleating. Under such conditions glass formation is also observed, and in fact the first observation of nucleation was a chance event, although since that time more systematic studies have been carried out. 

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