Ab initio study of ammonia adsorption states on an ice surface II: theoretical characterization of the surface bound state

The normal mode analysis was executed for the ammonia–water cluster, (NH3)3(H2O)9, i.e., a partial structure of the surface bound state via the density functional theory (DFT) calculation with the ammonia coverage of 0.33 ML on the (0 0 1) ice surface. In accordance with the recent infrared reflection absorption spectroscopy (IRAS) assignment, its characteristic vibrational bands were reproduced together with a new band prediction around 3248 cm−1 originating from the N–H hydrogen bond vibration. The theoretical characterization reveals complementarily a clear evidence of the surface bound state that was experimentally found for the first time.