Leino Markku, Viel Alexandra, Zillich Robert E
Institut de Physique de Rennes, UMR 6251, CNRS and Universite de Rennes I, F-35042 Rennes, France.
J Chem Phys. 2008 Nov 14;129(18):184308. doi: 10.1063/1.3009279.
We present theoretical studies of helium droplets and films doped with one electronically excited rubidium atom Rb( *) ((2)P). Diffusion and path integral Monte Carlo approaches are used to investigate the energetics and the structure of clusters containing up to 14 helium atoms. The surface of large clusters is approximated by a helium film. The nonpair additive potential energy surface is modeled using a diatomic in molecule scheme. Calculations show that the stable structure of Rb( *)He(n) consists of a seven helium atom ring centered at the rubidium, surrounded by a tirelike second solvation shell. A very different structure is obtained when performing a "vertical Monte Carlo transition." In this approach, a path integral Monte Carlo equilibration starts from the stable configuration of a rubidium atom in the electronic ground state adsorbed to the helium surface after switching to the electronically excited surface. In this case, Rb( *)He(n) relaxes to a weakly bound metastable state in which Rb( *) sits in a shallow dimple. The interpretation of the results is consistent with the recent experimental observations [G. Aubock et al., Phys. Rev. Lett. 101, 035301 (2008)].
我们展示了对掺杂有一个电子激发态铷原子Rb()（(2)P）的氦滴和氦膜的理论研究。采用扩散和路径积分蒙特卡罗方法来研究包含多达14个氦原子的团簇的能量学和结构。大团簇的表面用氦膜近似。非成对加和势能面采用分子中的双原子方案建模。计算表明，Rb()He(n)的稳定结构由以铷为中心的七个氦原子环组成，周围是类似轮胎的第二溶剂化壳层。当进行“垂直蒙特卡罗跃迁”时会得到一种非常不同的结构。在这种方法中，路径积分蒙特卡罗平衡从电子基态的铷原子吸附到氦表面的稳定构型开始，之后切换到电子激发表面。在这种情况下，Rb()He(n)弛豫到一个弱束缚的亚稳态，其中Rb()位于一个浅凹坑中。结果的解释与最近的实验观测结果[G. Aubock等人，《物理评论快报》101, 035301 (2008)]一致。
