Abstract:

Molecular dynamics (MD) simulations have been applied in the inverstigation of the spectra of aqueous solutions of nitrogen and oxygen. The flexible solute-solvent interaction potentials for N2-H2O and O2-H2O systems are prsented. The velocity autocorrelation functions (VACF) of the atoms of both solute and solvent molecules have been calculated according to the trajectories of atoms resulted from the MD simulations for the solutions. The properties of the resulted VACF’s are discussed and transformed into their spectral densities by Fourier transform. The resulted spectra of the atoms of solutes show their down shifts of the frequencies for the internal vibrational motion. The shifts are in agree well with the spectral results of Raman experiments which are in different conditions but with the similarity in their liquid surroundings. The spectra of rotational motions are also obtained from the simulations. The obtained spectra of rotation of the solutes show that the rotational motion is retarded by the interaction of the solvent. The simulation results also suggest that VACF is a very good approach for the investigation of the spectroscopy of solution and liquid.

Key words: Spectrum, Velocity autocorrelation function, Molecular dynamics simulation, Aqueous solution