AM1 and ab initio calculations on nitric acid mono- and trihydrates

Abstract

Geometries and interaction energies for HNO 3·H 2O and HNO 3·3H 2O have been computed with the AM1 and ab initio methods. STO-3G, MINI-1, 4-31G and 6–31 + +G** basis sets have been implemented in the latter. Adiabatic proton transfer energies have been computed for the monohydrate without and with the solvent effect. The latter is accounted for by the method of Tomasi and co-workers at the 4-31G level. The isolated monohydrate is more stable in the neutral form whereas the effect of high dielectric solvent cavity favours the ionic form. Geometry and interaction energy of the trihydrate have been computed using the AM1 and ab initio methods at minimal basis set levels only.