Heat of formation of the CF2++ dication: a theoretical estimate

Relative energies and ionization potentials of neutral and ionic fragments of CF4 were calculated using the coupled cluster single double (triple)/cor relation consistent triple zeta basis set ab initio method. The individual values were compared with available experimental and theoretical data to as sess the accuracy of this approach for these particular systems. In additio n, reaction enthalpies for possible fragmentation reactions were calculated . Maximum errors found were in the order of 5 kcal/mol (0.2 eV). The estima tion of the heat of formation of the CF2++ dication, derived from the calcu lations based on four different reactions, is 687 +/- 5 kcal/mol (29.8 +/- 0.2 eV). This value is considerably smaller than the one which follows from the appearance potential measurements (732 +/- 7 kcal/mol). (C) 2000 Elsev ier Science B.V.