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arXiv 1002.3829cond-mat.softcond-mat.stat-mechphysics.chem-ph
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SPC/E水的结构和动力学性质

Structural and dynamic properties of SPC/E water

M. G. Campo

摘要:

我已经研究了水的结构和动力学性质进行了一系列的分子动力学模拟的温度范围从213 K到360 K,使用简单点电荷扩展(SPC/E)模型。我使用GROMACS软件包对1185个水分子进行了等压等温模拟(1巴)。我用氧-氧径向分布函数、序参量和氢键分布函数量化了结构性质,而为了分析动力学性质,我研究了与历史相关的键关联函数和水分子均方位移的非高斯参数α_2(t)的行为。当温度降低时,平移(τ)和取向(Q)序参量线性相关,并且两者都增加,表明系统中的结构顺序增加。四个氢键的发生概率和Q都与T有相互依赖性,虽然氢键分布的分析允许更可靠地描述水的动力学和结构的变化。因此,在低于293 K的温度范围内,其中占主导地位的四个氢键结构的系统中,发生的笼效应和长时间的氢键的发生的增加。

英文摘要:

I have investigated the structural and dynamic properties of water by performing a series of molecular dynamic simulations in the range of temperatures from 213 K to 360 K, using the Simple Point Charge-Extended (SPC/E) model. I performed isobaric-isothermal simulations (1 bar) of 1185 water molecules using the GROMACS package. I quantified the structural properties using the oxygen-oxygen radial distribution functions, order parameters, and the hydrogen bond distribution functions, whereas, to analyze the dynamic properties I studied the behavior of the history-dependent bond correlation functions and the non-Gaussian parameter alpha_2(t) of the mean square displacement of water molecules. When the temperature decreases, the translational (tau) and orientational (Q) order parameters are linearly correlated, and both increase indicating an increasing structural order in the systems. The probability of occurrence of four hydrogen bonds and Q both have a reciprocal dependence with T, though the analysis of the hydrogen bond distributions permits to describe the changes in the dynamics and structure of water more reliably. Thus, an increase on the caging effect and the occurrence of long-time hydrogen bonds occur below 293 K, in the range of temperatures in which predominates a four hydrogen bond structure in the system.

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