Di Pietro Elisa, Pagliai Marco, Cardini Gianni, Schettino Vincenzo
Laboratorio di Spettroscopia Molecolare, Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italia.
J Phys Chem B. 2006 Jul 13;110(27):13539-46. doi: 10.1021/jp061620a.
When the free energy surface of the lithium hydroxide monohydrate crystal was explored, the high-pressure solid-state phase transition was determined. The high-pressure phase has been obtained through ab initio Car-Parrinello molecular dynamics simulation in the isothermic-isobaric ensemble. The recent metadynamics method has been applied to overcome the high activation energy barriers typical of rare events, like solid-state phase transition at high pressures. In the LiOH x H2O system, there are two kinds of H bonds: water-water and hydroxyl-water. The effect of the pressure has been investigated, to give further insight into the high-pressure phase. The strengthening of the H bonds of the system produces modifications in the water and the hydroxyl ion dipole electronic environment. The infrared spectra of both phases have been calculated and compared with experiments, and the assignment of the external modes has been discussed.
在探索一水合氢氧化锂晶体的自由能面时，确定了高压固态相变。通过在等温等压系综中进行从头算Car-Parrinello分子动力学模拟获得了高压相。最近的元动力学方法已被应用于克服罕见事件（如高压下的固态相变）典型的高活化能垒。在LiOH·H₂O体系中，存在两种氢键：水-水氢键和羟基-水氢键。研究了压力的影响，以进一步深入了解高压相。体系氢键的增强导致了水和羟基离子偶极子电子环境的改变。计算了两相的红外光谱并与实验进行了比较，并讨论了外部模式的归属。
