			15min:

COUPLED CLUSTER CALCULATIONS FOR COMPLEXES BETWEEN AN ARGON ATOM AND A
LINEAR MOLECULE OR CATION.

PETER BOTSCHWINA AND RAINER OSWALD, Institut für Physikalische Chemie, Universität Göttingen, Tammanstraß e 6, D-37077 Göttingen, Germany.

\noindent Geometric structures and various spectroscopic properties were calculated by the coupled cluster variant CCSD(T) for a number of complexes between an argon atom and linear neutral molecules (HCCH, HC₃N and HC₄H) and cations (HCNH⁺, HCCH⁺, HC₃NH⁺ and HC₄H⁺). The electronic ground state of Ar cdot cdot cdot HCCH⁺ has ²A₁ symmetry with a T shaped equilibrium structure. The linear form of Ar cdot cdot cdot HC₄H⁺ is energetically favoured over the T form, while the opposite holds for the corresponding neutral complex.