A NEW CLASS OF FREE STABLE DOUBLY NEGATIVE SYSTEMS - FIRST INVESTIGATIONS ON THE SIMON2- SERIES

Studies on several isomers of the C2On2- and Si2On2- series of dianion ic systems are performed at the Hartree-Fock, configuration interactio n, Moller-Plesset perturbation theory and outer-valence Green's functi on levels of theory. All examined C2On2- systems are predicted to be u nstable with respect to electron autodetachment. However, the analogue s silicon systems Si2On2- turn out to be electronically more stable th an the corresponding carbon species. For Si2O42- which marks the onset of electronic stability in the SimOn2- series the influence of the ba sis set and electron correlation on the geometrical parameters as well as on the electron detachment energy are studied in some detail. The possibility of decomposition via fragmentation or adiabatic electron l oss is discussed. A simple criterion to determine whether a given stru cture may represent a promising candidate for a stable dianion of the SimOn2- type is suggested. (C) 1995 American Institute of Physics.