arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2009.10201cond-mat.softcond-mat.mtrl-scicond-mat.stat-mechphysics.chem-phphysics.comp-ph
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压力变化下玻璃形成液体中结构弛豫与扩散的耦合

Coupling between structural relaxation and diffusion in glass-forming liquids under pressure variation

Anh D. Phan, Kajetan Koperwas, Marian Paluch, Katsunori Wakabayashi

摘要:

本文采用集体非线性朗之万方程(ECNLE)理论和分子动力学(MD)模拟方法研究了玻璃形成液体在不同压力下的结构弛豫和活化扩散。外部压力限制了单个分子在其笼中的局部运动,并引发合作运动的减慢。虽然ECNLE理论和模拟通常预测玻璃化转变温度和动态脆性随压力单调增加,但模拟表明,当压力高于1000 bar时,脆性降低。发现结构弛豫时间与逆扩散常数线性耦合。值得注意的是,这种耦合与压缩无关。理论计算与模拟结果在数量上吻合得很好,也与以前的工作一致。

英文摘要:

We theoretically investigate structural relaxation and activated diffusion of glass-forming liquids at different pressures using both the Elastically Collective Nonlinear Langevin Equation (ECNLE) theory and molecular dynamics (MD) simulation. An external pressure restricts local motions of a single molecule within its cage and triggers the slowing down of cooperative mobility. While the ECNLE theory and simulation generally predict a monotonic increase of the glass transition temperature and dynamic fragility with pressure, the simulation indicates a decrease of fragility as pressure above 1000 bar. The structural relaxation time is found to be linearly coupled with the inverse diffusion constant. Remarkably, this coupling is independent of compression. Theoretical calculations agree quantitatively well with simulations and are also consistent with prior works.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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