第117回計算科学コロキウムを、10月13日（金）に開催します。
多数のご来聴をお願い致します。

場所：筑波大学　総合研究棟B 110
日時：2017/10/13(金)　16:00-17：00
講演タイトル：Molecular Modeling of Water-Air and Ice-Air Interfaces
講演者氏名：永田勇樹　博士
講演者所属：Max Planck Institute for Polymer Research, Bonn Group

要旨：Structure and dynamics of Interfacial water  governs the atmospheric chemistry, chemical reactions on aqueous interface, and high surface tension of water. Nevertheless, molecular level insight into interfacial water is not fully gained. In this talk, I shall focus on the two topics – water evaporation and anomaly of ice surface around 200 K -. For water evaporation, I would reveal that water evaporation is -NOT- a completely stochastic process. The evaporation of water occurs in a time-ordered motion of multiple water molecules. [1] This challenges the variability of the free energy description for such an event. For anomaly of ice surface, we combined the molecular dynamics simulation with sum-frequency generation spectroscopy [2] and reveal that ice surface generates the maximum number of the hydrogen bond around 200 K, [3] which seems counterintuitive for the entropy increase in the thermodynamics second law. I will discuss how ice surface is melt with increasing temperature.

[1] Y. Nagata, K. Usui, and M. Bonn, Phys. Rev. Lett. 115, 236102 (2015)
[2] F. Perakis, …, Y. Nagata, Chem. Rev. 116, 7590 (2016)
[3] W. J. Smits, T. Fujie, …, Y. Nagata, Phys. Rev. Lett. 119, 133003 (2017)