
%0 Journal Article
%A Peel, JB 
%T Geometry Change on Ionization. Calculation of I<sub>V</sub>-I<sub>A</sub> Relaxation Energies for NH<sub>3</sub>, N<sub>2</sub>H<sub>4</sub> and CH<sub>3</sub>NH<sub>2</sub>
%J Australian Journal of Chemistry
%D 1986/08/01
%V 39
%N 8
%P 1281-1285
%K 
%R https://doi.org/10.1071/CH9861281
%U https://www.publish.csiro.au/paper/CH9861281 
%X Ab initio calculations on the NH3, N2H4 and CH3NH2 molecules and their respective ground- state cations represent the experimentally observed adiabatic and vertical ionization energies with reasonable accuracy. The unusually large IV - IA difference energy for N2H4 is a measure of the considerable change in geometry accompanying ionization. The calculated value of this relaxation energy at the MP3/6-31G** level is 2.3 eV , rather higher than the two experimental measurements of 1.55 eV , based on the band profile of the ultraviolet photoelectron spectrum, and 1.6-1.8 eV , determined from ion-molecule equilibrium measurements. The smaller IV-IA values for NH3 and CH3NH2 are calculated more accurately. Theoretical vibration frequencies are also obtained for the molecular cations. 
