Spectral shift of π→π* transition for p -nitroaniline based on a new expression of nonequilibrium solvation energy

According to the nonequilibrium solvation theory studies, a constrained equilibrium principle is introduced and applied to the derivations of the nonequilibrium solvation energy, and a reasonable expression of the spectral shift of the electronic absorption spectra is deduced. Furthermore, the lowest transition of p-nitroaniline (pNA) in water is investigated by time-dependent density functional theory method. In addition, the details of excited state properties of pNA are discussed. Using our novel expression of the spectral shift, the value of -0.99 eV is obtained for π→π* transition in water, which is in good agreement with the available experimental result of -0.98 eV.