Three-dimensional quantum dynamics study of vibrational predissociation of HeI_2 van der Waals molecule for low vibrational excitation using the time-dependent wave packet method

Three-dimensional quantum mechanical calculations for vibrational predissociation of HeI2(B) van der Waals molecules are presented using the time-dependent wave packet technique within the golden rule approxima tion.The total and partial decay widths,lifetimes,rates and their dependence on initial vibrational states were obtained for HeI2 at low initial vibrational excited levels.Our calculations show that the calculated tota decay widths,lifetimes and rates agree well with those extrapolated from experimental data available The predicted total decay widths as a function of initial vibrational states exhibit highly nonlinear behavior.The very short propagation time (less.than 1 ps) required in the golden rule wave packet calculation is determined by the duration time of the final state inter-action between the fragments on the vibrationally deexcited adiabatic potential surface.The final state interaction between the fragments is shown to play an important role in determining the final rotational distribution This interpreta tion clearly explains the dynamical effect that the final rotational distribution shifts to the lower rotational energy levels as the initial vibrational quantum number v increases.

含时黄金规则波包传播法对低初始振动激发HeI_2分子振动预离解的研究

采用含时黄金规则波包传播法，对低振动激发（ν＜１２）ｖａｎｄｅｒＷａａｌｓ分子ＨｅＩ２（总角动量Ｊ＝０）的振动预离解计算了总和部分衰变宽度。几乎对所有初始振动态，得到的总衰变宽度比线宽测量外推数据低约３０％。但是在很低振动激发（ν≤２）时。计算结果相当接近于实验外推数据。所得到的总衰变宽度随初始振动态的变化呈现一种非线性关系，这与较高振动激发的情况很相似。因此，低振动激发时总衰变宽度的变化不可能是源于离解机理改变的结果。衰变模式仍应是量子力学的。像在高振动激发时得到的结果一样，计算的转动态分布对初始振动还是不敏感的。