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Investigation of coarse-grained models across a glass transition
Soft Materials ( IF 1.2 ) Pub Date : 2020-01-20 , DOI: 10.1080/1539445x.2019.1711399
Ryan J. Szukalo 1 , W. G. Noid 1
Affiliation  

ABSTRACT

Due to their computational efficiency, coarse-grained (CG) models have become increasingly popular for simulating soft condensed matter. At least in principle, bottom-up CG models can reproduce the properties of all-atom (AA) models that are observable at the CG resolution. Unfortunately, the resulting effective potentials vary with thermodynamic state point, which can significantly limit the range of densities and temperatures for which the CG model is valid. In this study, we revisit these considerations for a 3-site CG model of ortho-terphenyl (OTP), which is a representative glass former. We employ force-matching and self-consistent pressure matching to parameterize the CG models. The resulting models accurately reproduce the OTP pair structure and pressure–volume equation of state at each state point for which they were parameterized. Above the glass transition, the effective potentials vary monotonically with temperature and density, as expected for molecular liquids. However, below the glass transition, these simple trends do not hold. Nevertheless, the effective potentials generally appear more sensitive to density than temperature. Moreover, despite this state-point dependence, the potentials appear reasonably transferable in the sense that they reasonably describe OTP across a fairly wide density and temperature range that spans the glass transition. Interestingly, the glass phase potentials appear most accurate and transferable. Conversely, the potentials parameterized near the glass transition appear least accurate and transferable.



中文翻译:

研究玻璃过渡过程中的粗粒度模型

摘要

由于它们的计算效率,用于模拟软冷凝物的粗粒度(CG)模型已变得越来越流行。至少原则上,自下而上的CG模型可以重现在CG分辨率下可观察到的全原子(AA)模型的属性。不幸的是,所产生的有效电势随热力学状态点而变化,这会大大限制CG模型有效的密度和温度范围。在这项研究中,我们重新审视了邻位三联苯(OTP)的3位CG模型的这些考虑,这是一种典型的玻璃成型剂。我们采用力匹配和自洽压力匹配来对CG模型进行参数化。生成的模型可以精确地重现OTP对的结构和参数的每个状态点的压力-体积状态方程。在玻璃化转变温度以上,有效电势随温度和密度单调变化,这是分子液体所期望的。但是,在玻璃化转变以下,这些简单的趋势不成立。然而,有效电势通常看起来比温度对密度更敏感。此外,尽管有这种状态点依赖性,但电位在合理范围内可以合理转移,因为它们可以合理地描述跨越玻璃化转变的相当宽的密度和温度范围内的OTP。有趣的是,玻璃相电势似乎最准确且可转移。相反,在玻璃化转变附近参数化的电势似乎最不准确且不可转移。在玻璃转变以下,这些简单趋势不成立。然而,有效电势通常看起来比温度对密度更敏感。此外,尽管有这种状态点依赖性,但电位在合理范围内可以合理转移,因为它们可以合理地描述跨越玻璃化转变的相当宽的密度和温度范围内的OTP。有趣的是,玻璃相电势似乎最准确且可转移。相反,在玻璃化转变附近参数化的电势似乎最不准确且不可转移。在玻璃转变以下,这些简单趋势不成立。然而,有效电势通常看起来比温度对密度更敏感。此外,尽管有这种状态点依赖性,但电位在合理范围内可以合理转移,因为它们可以合理地描述跨越玻璃化转变的相当宽的密度和温度范围内的OTP。有趣的是,玻璃相电势似乎最准确且可转移。相反,在玻璃化转变附近参数化的电势似乎最不准确且不可转移。从可以合理地描述跨越玻璃化转变的相当宽的密度和温度范围内的OTP的意义上讲,电势似乎可以合理地转移。有趣的是,玻璃相电势似乎最准确且可转移。相反,在玻璃化转变附近参数化的电势似乎最不准确且不可转移。从可以合理地描述跨越玻璃化转变的相当宽的密度和温度范围内的OTP的意义上讲,电势似乎可以合理地转移。有趣的是,玻璃相电势似乎最准确且可转移。相反,在玻璃化转变附近参数化的电势似乎最不准确且不可转移。

更新日期:2020-01-20
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