Path Integral Monte Carlo Calculations of Calcium-Doped 4He Clusters

The energetics and structures of HeNCa clusters have been studied by means of path integral Monte Carlo calculations. Sizes ranging between N=10 and 40 helium atoms were considered at T=1, 1.5, and 2 K. Radial and angular distributions have been analyzed in detail to investigate the geometry of the bound systems. The comparison of the results obtained with two current He-Ca interactions (Kleinekathofer, Chem. Phys. Lett. 2000, 324, 40, and Lovallo and Klobukowski J. Chem. Phys. 2004, 120, 246) reveals substantial differences regarding the precise location of the Ca impurity with respect to the helium droplet. Whereas the use of the first potential yields a doped cluster in which the Ca atom is solvated inside a helium cage, predictions with the much weaker He-Ca potential by Lovallo and Klobukowski correspond to the formation of a dimple at the surface of the outer He atoms to host the Ca atom, a situation which is consistent with the experimental findings for the system. (C) 2014 Wiley Periodicals, Inc.