Miguel Beatriz, Zúñiga José, Requena Alberto, Bastida Adolfo
Departamento de Ingeniería Química y Ambiental, Universidad Politécnica de Cartagena, 30203 Cartagena, Spain.
Departamento de Química Física, Universidad de Murcia, 30100 Murcia, Spain.
J Chem Phys. 2016 Dec 28;145(24):244502. doi: 10.1063/1.4972128.
The molecular dynamics with quantum transitions method is used to study the vibrational relaxation of the OD stretching mode of HOD dissolved in liquid HO water at 303 K. All the vibrational modes of the solute and solvent molecules that participate in the relaxation process are described by quantum mechanics, while the rotational and translational degrees of freedom are treated classically. A modification of the water intramolecular SPC/E (Simple Point Charge/Extended) force field providing vibrational frequencies in solution closer to the experimental values is proposed to analyze the influence of the vibrational energy gaps on the relaxation channels. The relaxation times obtained are in satisfactory agreement with experimental values. The energy transfer during the relaxation process alters significantly the H-bond network around the HOD molecule. The analysis of the vibrational transitions during the relaxation process reveals a complex mechanism which involves the participation of both intra- and intermolecular channels and provides a compromise for the different interpretations of the experimental data reported for this system in recent years.
采用含量子跃迁的分子动力学方法研究了303K下溶解于液态重水（HO）中的重水合氢离子（HOD）的OD伸缩振动模式的振动弛豫。溶质和溶剂分子参与弛豫过程的所有振动模式均用量子力学描述，而转动和平动自由度则采用经典处理。提出了一种对水分子内SPC/E（简单点电荷/扩展）力场的修正方法，该方法能使溶液中的振动频率更接近实验值，以分析振动能隙对弛豫通道的影响。得到的弛豫时间与实验值吻合良好。弛豫过程中的能量转移显著改变了HOD分子周围的氢键网络。对弛豫过程中振动跃迁的分析揭示了一种复杂的机制，该机制涉及分子内和分子间通道的参与，并为近年来该系统实验数据的不同解释提供了折衷方案。
