title: A density functional study of the structure of small OCS@3He(N) clusters.
abstract: Kohn-Sham density functional calculations are reported for the structures of clusters consisting of a carbonyl sulfide (OCS) molecule with N = 1, 8, 18, and 40 attached (3)He atoms. The N = 1 cluster ground state is highly localized at the molecular waist (donut ring position), but for higher levels of excitation becomes increasingly delocalized. The first magic cluster with 8 atoms has a significant density at both ends of the molecule in addition to the donut ring. With N = 18 (3)He atoms the molecule is enclosed by a magic number closed shell. Another magic stable structure consisting of two nearly isotropically spherical closed shells is found at N = 40. A comparison with calculations for the same sized (4)He clusters show some important similarities, e.g., pile up at the donut ring position but altogether a more diffuse, less anisotropic structure. These results are discussed in the light of the recently analyzed infrared spectra measured in large pure (3)He droplets (N ≈ 1.2 × 10(4)) [B. Sartakov, J. P. Toennies, and A. F. Vilesov, J. Chem. Phys. 136, 134316 (2012)]. The moments of inertia of the 11 atom spherical shell structure, which is consistent with the experimental spectrum, lies between the predicted moments of inertia for N = 8 and N = 18 clusters. Overall the calculations reveal that the structures and energies of small doped (3)He are only slightly more diffuse and less energetic than the same (4)He clusters.
authors: Departament E.C.M., Facultat de Física, and IN²UB, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona, Spain.
authors: David
authors: D
authors: Mateo
authors: Martí
authors: M
authors: Pi
authors: Jesús
authors: J
authors: Navarro
authors: J Peter
authors: JP
authors: Toennies
mesh_terms: D006371:Helium / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013461:Sulfur Oxides / Q000737:chemistry*
chemical_list: D013461:Sulfur Oxides; D006371:Helium; C010063:carbonyl sulfide