Molecular-Dynamics Simulations for the Density Autocorrelation Function in a Supercooled Fluid Phase |
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Authors: | K Uehara T Muranaka H Miyagawa M Takasu Y Hiwatari |
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Institution: | 1. Department of Physics , Faculty of Science, Kanazawa University , Kanazawa, Ishikawa, 920-11, Japan;2. Department of Physics , Faculty of Science, Kanazawa University , Kanazawa, Ishikawa, 920-11, Japan;3. Integral Research Institute, Taisho Seiyaku Co., Ltd , Ohmiya, Saitama, 330, Japan |
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Abstract: | Abstract We have re-calculated the self part of the density autocorrelation function Fs(k, t) (incoherent scattering function) for the binary soft-sphere fluid with a much longer molecular-dynamics (MD) simulation than our previous MD calculations, and with a larger system size (N = 4000) to a longer time window as well as to study a system-size dependence, if it exists. The full density autocorrelation function F(k, t) was also computed. It is found that all F(k, t)'s that we have computed in this work can be fitted over a wide range of time steps (at least over three figures of the decay) by a Williams-Watts stretched exponential function Fs(k, t) = A exp — (t/t 0)β], where A, β and t 0 are adjustable parameters. Other significant dynamical behaviours were also presented in mean square displacements and non-Gaussian parameters for highly supercooled fluids with N = 4000. The present results are compatible to our previous computations with N = 500, but a significant size dependence is suggested. |
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Keywords: | Density autocorrelation function α relaxation stretched exponential decay |
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