ACCURATE HEATS OF FORMATION FOR SIFN AND SIFN-4(, FOR N=1)

Accurate beats of formation are computed for SiFn and SIFn+, for n = 1 - 4. The vibrational frequencies are determined at the B3LYP level of theory. The energetics are determined at the CCSD(T) level of theory. Basis set limit values an obtained by extrapolation; In those cases w here the CCSD(T) calculations become prohibitively large, the basis se t extrapolation is performed at the MP2 level, The temperature depende nce of the hear of formation, heat capacity, and entropy are computed for the temperature range 300-4000 It and fit to a polynomial. The CCS D(T) bond energies are compared with those obtained at the B3LYP, MP2, G2, and G2MP2 levels of theory.