IMPORTANCE OF BIMOLECULAR INTERACTIONS IN DEVELOPING EMPIRICAL POTENTIAL FUNCTIONS FOR LIQUID-AMMONIA
IMPORTANCE OF BIMOLECULAR INTERACTIONS IN DEVELOPING EMPIRICAL POTENTIAL FUNCTIONS FOR LIQUID-AMMONIA
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DOI：
10.1021/j100138a028
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发表时间：
1993-09-09
影响因子：
--
通讯作者：
GEORGE, TF
中科院分区：
文献类型：
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作者：
GAO, JL;XIA, XF;GEORGE, TF
一个四位的分子间势能函数的NH3已经开发和测试的Monte Carlo统计力学模拟的液体在其沸点（-33.35 ℃）和1大气压。势产生良好的热力学结果液氨，而液体的结构，其特征在于通过径向分布函数和氢键分析。结果表明，每个氨平均形成三个氢键，液体中含有氢键单体的缠绕链。在液体中，大致线性的氢键占主导地位。计算结果还与Ferrario等人提出的五位模型进行了比较。虽然计算得到的汽化热、液体密度和径向分布函数与我们的结果和实验数据雅阁，但令人惊讶的是，两种理论模型在二聚体和液体结构上存在显著差异。的结构差异是由于不切实际的二聚体结构的发生与捐赠的氢键的氨孤对电子对的相对侧的液体从模型的Ferrario等人。相反，从头计算和本四网站模型预测这些结构没有稳定的复合物。这些研究结果强调了在开发流体模拟的势函数时具体考虑双分子相互作用的重要性，并表明如果势函数单独拟合以再现凝聚相性质，则可能会获得错误的结果。
A four-site intermolecular potential function for NH3 has been developed and tested in Monte Carlo statistical mechanics simulations of the liquid at its boiling point (-33.35-degrees-C) and 1 atm. The potential yields good thermodynamic results for liquid ammonia, while the structures of the liquid are characterized through radial distribution functions and hydrogen-bonding analyses. The results indicate that each ammonia forms on average three hydrogen bonds and the liquid contains winding chains of hydrogen bonded monomers. Roughly linear hydrogen bonds predominates in the liquid. The results were also compared with those obtained using the five-site model developed by Ferrario et al. Although the computed heat of vaporization, liquid density, and the radial distribution functions are in good accord with our results and experimental data, to our surprise, a significant difference in the dimer and liquid structures exists between the two theoretical models. The structural difference is due to the occurrence of unrealistic dimer structures with donation of hydrogen bonds to the opposite side of the ammonia lone pair in the liquid from the model of Ferrario et al. In contrast, both ab initio calculations and the present four-site model predict no stable complexes for these structures. These findings emphasize the importance of specific consideration of bimolecular interactions in developing potential functions for fluid simulations and suggest that erroneous results might be obtained if the potential functions are fitted to reproduce the condensed-phase properties alone.