Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA.
J Chem Phys. 2010 Nov 14;133(18):184104. doi: 10.1063/1.3503500.
An efficient method is presented for rigorous quantum calculations of atom-molecule and molecule-molecule collisions in a magnetic field. The method is based on the expansion of the wave function of the collision complex in basis functions with well-defined total angular momentum in the body-fixed coordinate frame. We outline the general theory of the method for collisions of diatomic molecules in the (2)Σ and (3)Σ electronic states with structureless atoms and with unlike (2)Σ and (3)Σ molecules. The cross sections for elastic scattering and Zeeman relaxation in low-temperature collisions of CaH((2)Σ(+)) and NH((3)Σ(-)) molecules with (3)He atoms converge quickly with respect to the number of total angular momentum states included in the basis set, leading to a dramatic (>10-fold) enhancement in computational efficiency compared to the previously used methods [A. Volpi and J. L. Bohn, Phys. Rev. A 65, 052712 (2002); R. V. Krems and A. Dalgarno, J. Chem. Phys. 120, 2296 (2004)]. Our approach is thus well suited for theoretical studies of strongly anisotropic molecular collisions in the presence of external electromagnetic fields.
本文提出了一种在磁场中进行原子-分子和分子-分子碰撞的严格量子计算的有效方法。该方法基于在体坐标系中具有明确定义总角动量的基函数中展开碰撞复合物的波函数。我们概述了用于（2）Σ和（3）Σ电子态的双原子分子与无结构原子以及不同的（2）Σ和（3）Σ分子之间碰撞的方法的一般理论。对于 CaH((2)Σ(+))和 NH((3)Σ(-))分子与（3）He 原子在低温下的弹性散射和塞曼弛豫的截面，随着基组中包含的总角动量态数的增加迅速收敛，与以前使用的方法相比，计算效率显著提高（> 10 倍）[A. Volpi 和 J. L. Bohn，Phys. Rev. A 65, 052712 (2002)；R. V. Krems 和 A. Dalgarno，J. Chem. Phys. 120, 2296 (2004)]。因此，我们的方法非常适合在存在外电磁场的情况下对强各向异性分子碰撞进行理论研究。
