Density functional study of α-amino acids: structural, energetic and vibrational properties

Abstract

The structural, energetic and vibrational properties of the 20 standard α-amino acids, in each of several different low-energy conformations, have been investigated using all-electron density-functional theory. The Becke–Perdew exchange-correlation potential within the generalized gradient corrections to the local density approximation exchange and correlation energy was used, along with a Slater-type expansion of the Kohn–Sham orbitals. The structures and bond lengths, conformation energies, and infrared vibrational spectra of the stable conformers of these molecules have been predicted and various features, including those arising due to intramolecular hydrogen bonding, identified. The results of our accurate ab initio study, the most comprehensive to date, are in good agreement with the few earlier gas-phase experimental and theoretical results available from the literature, and provide a benchmark for further experiments and for obtaining a deeper understanding of this vital class of biomolecules.