Glass structures molecular dynamics simulations

Karthikeyan A., Almeida RM. Structural anomaly in sodium germanate glasses by molecular dynamics simulation. J. Non-Cryst. Sohds 2001 281 152-161 Klug H.P., Alexander L.E. X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials. John Wiley Sons, New York, USA, 1994 Loshmanov A.A., Sigaev V.N., Yamzin LI. Sov. Phys. Cryst. 1974 19 168 Manaila R., Zaharescu. Medium range order in high surface area amorphous silicas. J. Mater. Sci. 1990 25 2095-2099... 

J. Du, A.N. Cormack, The medium range structure of sodium silicate glasses a molecular dynamics simulation. J. Non-Cryst. Solids 349,66-79 (2004)... 

Structural Insight into Transition Metal Oxide Containing Glasses by Molecular Dynamic Simulations... 

G. Malavasi, A. Pedone, M.C. Menziani, Study of the structural role of gallium and ahuninum in 45S5 bioactive glasses by molecular dynamics simulations. J. Phys. Chem. B 117(15), 4142-50 (2013)... 

A. Tdocca, Structural models of bioactive glasses from molecular dynamics simulations. Proc. R. Soc. A 465(2104), 1003-1027 (2009)... 

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)... 

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... 

As will be apparent in Chapter 4, MD simulations have made major contributions to our understanding of the structures and dynamical properties of solids. Problems and processes simulated include phase transitions (e.g. Impey et al., 1985 Meyer and Ciccotti, 1985), orientation dynamics in molecular crystals (e.g. Dove and Pawley, 1984) and ionic and diffusion (e.g. Gillan and Dixon, 1980 Vashishta and Rahman, 1978). In addition, they have been used to study melting and, as noted above, to prepare glass structures by a simulated melt-quench cycle as described by Vessal in Chapter 12. 

Parker, J.M., 1987, Molecular dynamics simulations of fluorozirconatc glass structure, in Halide Glasses for Infrared Fiberoptics, ed. R.M. Almeida (Martinus Nijhoff, Dordrecht) pp. 119-136. 

The principal benefit of molecular dynamics simulations derives from its atomic scale treatment the models produce a picture of the atomic structure, which may be visualised directly using current state of the art imaging techniques, such as video production. This, of course, is in addition to the calculation of the standard range of structural information, such radial distribution functions, which can be measured directly. The problem with these measurements, obtained from neutron or x-ray scattering studies, is that they are essentially one dimensional, because of the isotropic nature of glass. A full three dimensional reconstruction of the atomic structure is not possible, therefore, so recourse to modeling is somewhat essential. 

The local and medium-range structure of the CaAl2Si30io glass generated by classical molecular dynamics simulations has been compared to A1 and 0 NMR NMR and MQMAS experiments. These were found to be in good agreement. 

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