Ab initio and density functional theory calculations of molecular structure and vibrational spectrum of ethyl azidoacetate

Here we report ab initio and density functional results for molecular properties of ethyl azidoacetate (N3CH2COOC2H5) and for the corresponding singly ionized structure (N3CH2COOC2H5+). Ab initio ionization energies based on Koopmans' theorem are in excellent agreement with the experimental data from ultraviolet photoelectron spectroscopy. DFT adiabatic energy differences between neutral and ionized structures are very sensitive to electronic correlation effects and are not in very good agreement with experiment. The results for the structure and vibrational frequencies are compared with the experimental data of related molecular structures. (C) 1999 Elsevier Science B.V. All rights reserved.