HONO2 Adsorption on Ice Surfaces

The Adsorption of HONO₂ on an ice surface was modeled using Gaussian 09 and performing Density Functional Theory analysis using B3LYP/6-31++G(d,p) level of theory. We looked at the interaction of HONO₂ with a water 28 cage.  We found two distinctive adsorption structures: (1) a perpendicular adsorptions were we have two hydrogen bonds and (2) a parallel adsorption characterized by the formation of three hydrogen bonds.  Both structures show a strong hydrogen bond interaction.  A Natural Bond Orbital Analysis (NBO) of these structures shows second order energies of 45 kcal/mol and 43 kcal/mol for the perpendicular and parallel adsorptions respectively.  Molecular dynamic simulations suggest that HONO₂ prefers to be on the surface of the water cluster.  This is also confirmed by our quantum mechanical computations where partially enclosed HONO₂ specie optimized as a parallel adsorption on the surface of our cluster.