Configuration interaction calculations on the cyclic carbon clusters C8, C10, Pt@C8 and Pt@C10 and their anionic forms

Ab initio single plus double excitations configuration interaction calculations in the context of relativistic effective core potentials are reported for C8, C10, Pt@C8 and Pt@C10 clusters in their neutral and ionic forms. The predicted geometries of cyclic C82- and C102- correctly justify double coincidence mass spectra results as compared to linear C82- and C102-. The effects of Pt encapsulation in these clusters are discussed in terms of binding affinities and equilibrium geometries. The Pt@C8 and Pt@C10 clusters have binding affinities of 5900 kJ/mol and 7900 kJ/mol, respectively. Binding energies for Pt encapsulation are only favorable for the doubly charged carbon clusters, indicating that stable Pt encapsulation only occurs for the C82- and C102- clusters.