Structural and Dynamic Properties of Water on the GaN Polar Surface

• Published in: Journal of physical chemistry. C 2011-11, Vol.115 (45), p.22444-22450
• Main Authors: Tan, Osbert Zheng, Tsai, K. H, Wu, Michael C. H, Kuo, Jer-Lai
• Format: Article
• Language: English
• Subjects: C: Surfaces, Interfaces, Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp2070166

The structural and dynamic properties of water on the GaN(0001) polar surface are investigated via classical molecular dynamics simulations. The interfacial molecules are observed to have enhanced structural ordering and slowed-down dynamics compared to the liquid bulk; these unique properties are evidenced in the slower reorientational relaxation, smaller diffusion constant, and longer residence lifetime for water located at the surface region up to ∼7 Å from the substrate. Further analysis of the vibrational spectra at low frequencies shows that both the hydrogen bond network bending and the hydrogen bond stretching bands at the interface shift to the blue compared to those in the bulk, due to the strong coupling between the O atom of water and the Ga sites. The distinct spectral features along with the anisotropy of the hydrogen bond distributions of the interfacial water are complex results determined by both the substrate–water and water–water interactions.