Study on the Structure, Frequency Mode, and Dielectric Properties of Glycolic Acid in the Physiological Salt Solution by Molecular Dynamics

Molecular dynamics (MD) study on glycolic acid in the physiological salt solution has been performed, which is a model of a biofuel cell. The structure and charge distribution of glycolic acid in aqueous solution used in MD is beforehand optimized by Gaussian09 utilizing the density functional theory. MD is performed in the NPT constant condition, i.e. the number of particles, pressure, and temperature of MD cell are definite. The structure difference of the glycolic acid and oxalic acid is detected by the water distribution around the molecules using the pair distribution functions, gij(r), and the frequency dependent diffusion coefficients, Di(?). The transport properties for glycolic acid anion and oxalic acid anion are quite different, which may be attributed to the structural difference. The anomalous dielectric constant of the solution, i.e. about 12 times larger than that of water, has been obtained, which may be attributed to the ion pair formation in the solution This fact may be explained by the large dipole moment formation in the solution, however the further analysis is left for the future study.