Theoretical study of the photoelectron spectrum of ethyl formate: Ab initio and density functional theory investigation
Department of Theoretical Physics and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
Received: 8 June 2013
Revised: 9 August 2013
Published online: 23 October 2013
The first ionization energy and associated photoelectron spectrum of ethyl formate are investigated with quantum chemistry calculations. The geometries, harmonic vibrational frequencies and first ionization energy are computed at the Hartree-Fock (HF) and at the second order Møller-Plesset perturbation theory (MP2). Moreover, accurate ionization energies are obtained with the Coupled-Cluster theory including singles and doubles excitations (CCSD) as well as singles, doubles and perturbative triples excitations (CCSD(T)). Then, these ab initio results are assessed with respect to experimental values. Additionally, the ionization energies are also calculated with the computationally attractive density functional theory (DFT). In this case the accuracy of several exchange-correlation functionals is evaluated by comparison with the ab initio and experimental results. In a next step, the vibrational structure of the photoelectron spectrum is simulated at the HF, MP2 and DFT levels via the calculation of the Franck-Condon factors. These simulations are compared to the experimental photoelectron spectrum and allow an accurate reproduction of the vibrational progression.
© EDP Sciences, Springer-Verlag, 2013