N2,O2水溶液光谱的分子动力学模拟

用分子动力学模拟方法研究了N2和O2水溶液的光谱性质．给出了能描述分子内部运动的溶质－溶剂相互作用势．对溶质和溶剂原子的速度自相关函数（VACF）作了计算．讨论了所得VACF的性质并计算了其谱密度．溶质分子振动谱出现的红移，与液态N2，O2的Raman实验结果相吻合．模拟得出的转动谱表明了溶剂分子对溶质转动运动的阻滞，模拟结果也表明VACF计算对溶液和液体光谱的研究十分有效．

Molecular Dynamics Simulations for the Spectra of N_2 and O_2 Aqueous Solutions

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 auto correlation 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 wen 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.