Theoretical Determinations of Ionization Potential and Electron Affinity of Glycinamide Using Density Functional Theory

Abstract

Accurate vertical (adiabatic) ionization potential (IP) and valence electron affinity (EA) of glycinamide, including its possible conformers, have been determined employing density functional theory (B3LYP) with 6-311++G** and 6-311G** basis sets, respectively. The calculated adiabatic IPs are 8.60, 8.57, 8.52, and 8.49 eV for conformer IA, IIA, IIIA, and IV, respectively, decreasing gradually with the decreasing of their relative stabilities. Comparisons with glycine indicate that the substitute of −NH2 for −OH in glycine decreases its ionization potential. In various solutions, IPs decrease apparently with respect to those in the gas phase. All electron affinities of glycinamide conformers are negative values in the gas phase, indicating that the anionic states are unstable with respect to electron autodetachment vertically and adiabatically. On the contrary, all of the adiabatic EAs in solution possess positive values and become larger and larger with the increasing of dielectric constants. Additionally, the IPs and EAs for hydrated glycinamide with one, two, and three water molecules have been explored. Finally, all kinds of chemical quantities associated with the IP and EA, such as electronegativity, chemical potential, chemical hardness, and chemical softness, have also been determined.