分子动力学模拟纳米尺寸限制体系下氩溶液中I2的振动能量弛豫

Molecular Dynamics Simulation of the Vibrational Energy Relaxation of I_2 in Nano-confined Argon Solution

利用平衡态分子动力学方法(EMD)模拟了纳米尺寸限制球壳内I2在Ar溶液中的振动能量转移.计算并讨论了I2振动能量弛豫时间T1随球壳半径、溶剂密度的变化规律.通过分子间相互作用分析,在原子、分子水平上,揭示了随着球壳半径的减小,T1呈逐渐增大趋势的原因.结果表明,球壳的几何限制效应和表面作用对受限溶液密度分布的影响较大,从而导致溶质振动弛豫的显著变化.此外,非限制体系模拟显示,非平衡态分子动力学(NEMD)方法可以得到与平衡态分子动力学方法较一致的振动能量弛豫时间T1.

The vibrational energy transfer of I2 in argon solution confined in a nano-spherical cavity has been simulated by the equifibrium molecular dynamics （EMD） approach. The solute vibrational energy relaxation time T1, as a function of the radius of the spherical cavity and the solvent density, is calculated and discussed. According to the analysis of intermolecular interactions at atomic and molecular level, the reason of T1 increasing with the cavity radius decreasing is explored. The results showed that the geometry confinement and surface effect played an important role in the solvent distribution, which would influence the vibrational relaxation significantly. In addition, the simulations of bulk system indicated the values of T1 obtained by EMD and non-equilibrium molecular dynamics （NEMD） were in good agreement for I2/Ar system.