Abstract—We study the mechanism and energetics of proton transfer (PT) in ammonia-nitric acid systems by employing ab initio calculations. PT does not occur in the single ammonium nitrate unit (NH ₃ –HNO₃; monomer) without the application of an external electric field. In contrast, PT is energetically favorable in oligomers (NH   ₄   NO  ₃  ) _n=2~8  du e to the internal polarization - resulting in the a  mmonium and nitrate ions, NH ₄  +···NO₃ –. Additionally, we study th e energetics of ammonium nitrate oligomerization using simple energy decomposition. The classical electrostatic interaction plays a principal role in the studied oligomerization, whereas the charge transfer interaction is not significant. Consequently, PT in the ammonium nitrate oligomer system enhances the internal electrostatic interaction, resulting in an ionic form with remarkable stability even in the gas phase.

Index Terms—Ab initio calculation, ammonium nitrate oligomers, energetic stabilization, proton transfer.

Jo Takeuchi and Kyozaburo Takeda are with the Department of Electrical Engineering and Bioscience, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan, and the first author is also with the Department of Human Science, Takachiho University, Suginami, Tokyo 168-8508, Japan (e-mail: takeuchi-j@takachiho.ac.jp).

Cite: Jo Takeuchi and Kyozaburo Takeda, "Theoretical Study on Proton Transfer and Energetics in Ammonium Nitrate (NH₄NO₃)_n Cluster System," International Journal of Applied Physics and Mathematics vol. 4, no. 1, pp. 5-8, 2014.