He-HBr体系各向异性势及非弹性散射截面的理论研究

首先用BFW势函数形式拟合在CCSD(T)/aug-cc-pVQZ理论水平下计算的He-HBr相互作用能数据,得到了He原子与HBr分子各向异性势;并与ESMSV势进行比较,验证了拟合势的可靠性;然后采用公认的精确度较高的CC近似方法计算了He-HBr碰撞体系能量在150meV下He原子和HBr分子碰撞的转动激发微分截面和分波截面,总结了该碰撞体系非弹性散射截面的变化规律.研究表明:①拟合势较好地描述了He-HBr系统相互作用的各向异性特征;利用碰撞体系分子间势的量子化学从头计算结果,可解决势能参数难以确定的问题.②低激发态被激发的几率要远远大于高激发态被激发的几率;激发态越高,大角散射的几率越大.③尾部效应仅在低激发态中产生,高激发态不产生尾部效应.

Theoretical study of the anisotropic potential and inelastic scattering cross sections for He-HBr system

A new anisotropic potential for He-HBr system is obtained on the basis of BFW potential function by fitting the interaction energy data,which have been calculated at the theoretical level of the single and double excitation coupled-cluster method with noniteractive perturbation treatment of triple excitation CCSD(T).And reliability of the fitted potential is confirmed by comparing it with ESMSV potential.Then the rotational-excitation differential cross sections and partial cross sections at the energy of 150 meV for collisions between He atoms and HBr molecules are calculated by using CC(Close-Coupling) method.Furthermore,the changing regularity of the inelastic scattering cross sections for He-HBr system is summed up.The research shows that the fitted potential is characteristic of describing anisotropism better for He-HBr system,and that is more easier to determine the potential parameters by applying to the results of ab initio calculation for the collision systems.In addition,the excited probabilities of lower exciting states are far off bigger than ones of higher exciting states.The higher exciting states are,the bigger probabilities of big angle scatterings are.And the tail effect emerges only in lower exciting states,there isn't tail effect in higher exciting states.