Electron propagator theory study of 2-aminoethanol conformers

Thirteen low-lying conformers of 2-aminoethanol (AE) has been studied by ab initio calculations at B3LYP, MP2, MP3 and MP4 (SDTQ) levels of theory with aug-cc-pVDZ basis set. The gauche′-Gauche-gauche′ (g′Gg′) conformer having the intramolecular hydrogen bond (HB) OH⋯N is the most stable one. Vertical ionization energies of the two outer valence molecular orbitals for each conformer predicted with the electron propagator theory are in good agreement with the experimental data in the literature and the temperature dependence of photoelectron spectra (PES) is interpreted when taken into account the Boltzmann populations of the conformers. Natural bond orbital (NBO) analyses exhibit a remarkable influence on the molecular electronic structures by the strong intramolecular HB OH⋯N and the relative weak intramolecular HB NH⋯O, leading to the significantly lowered energy levels of the occupied lone-pair molecular orbitals.