We present an ab initio-based force-field for silver ion interactions with water and ammonia. Compared to quantum calculations, our model allows for rather large-scale molecular dynamics simulations of silver solutions of aqueous ammonia. For a series of NH₃:H₂O ratios ranging from 1 to 20 mol. %, Ag⁺ ions were mainly found as octahedral ${[\mathrm{Ag}{({\mathrm{NH}}_3)}_{\mathrm{x}}({\mathrm{H}}_2\mathrm{O})]}_{6-x}^{+}$ coordination complexes with preferential values of x ranging from 0 to 3. In the first coordination structure, water $\leftrightarrow$ ammonia exchanges occur within a 1-3 ps time scale and, depending on the NH₃ concentration, imply significant fluctuations of x covering the whole range from 0 to 6. Based on ns-scale molecular dynamics simulations, chemical potentials are derived for all Ag⁺ coordination species as functions of temperature and ammonia concentration. Moreover, we compare the diffusion constants of the [Ag(H₂O)₆]⁺ to [Ag(H₂O)₃(NH₃)₃]⁺ coordination complexes, based on the solutions of the corresponding ammonia content.

中文翻译：

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氨水溶液中Ag ^+的溶剂化结构和动力学：分子模拟研究

我们提出了一个基于从头算的力场，用于银离子与水和氨的相互作用。与量子计算相比，我们的模型可以对氨水银溶液进行大规模的分子动力学模拟。对于一系列的NH ₃：H ₂ O比率，范围为1至20摩尔。％，Ag ⁺离子主要为八面体${[银{（{\mathrm{NH}}_3）}_{\mathrm{X}}（{\mathrm{H}}_{\mathrm{2个}}\mathrm{Ø}）]}_{6-X}^{+}$x的优先值介于0到3之间的配位化合物。在第一个配位结构中，水$\leftrightarrow$氨交换发生在1-3 ps的时间范围内，并且取决于NH ₃浓度，这意味着x的波动范围从0到6。基于ns尺度的分子动力学模拟，可以得出所有Ag的化学势⁺配合物种类随温度和氨浓度的变化而变化。此外，基于相应氨含量的溶液，我们比较了[Ag（H ₂ O）₆ ] ⁺与[Ag（H ₂ O）₃（NH ₃）₃ ] ⁺配位化合物的扩散常数。