EPR Parameter Calculations of Radiation and Mechanically Induced Radicals in Alpha keratin Based on Density Functional Theory

In this research, the geometrical parameters, the spin density of atoms, and the EPR parameters of radiation and mechanically induced radicals in alpha keratin were investigated using density functional theory. Generally, various factors such as hydrogen bonds and temperature impact the EPR parameters. First, cluster calculations were used to study the effect of hydrogen bonds, and then ab-initio molecular dynamics calculations were used to investigate the simultaneous effects of hydrogen bonds and temperature. Variation of the g tensor components and the coupling constants are dependent on the change of the geometrical parameters and the spin density of the atoms. Due to being a small variation of the geometrical parameters and the spin density of the atoms between the cluster model and the molecular dynamics for the radiation and the mechanically induced radicals, the difference between calculated EPR parameters by means of two mentioned models is insignificant. The result shows a good agreement between the calculated EPR parameters and the experimental results. Also, due to the considering of the ambient temperature effect, the obtained results from the molecular dynamic calculation have a better agreement with the experimental data in comparison to the cluster model.