A DENSITY-FUNCTIONAL INVESTIGATION ON THE STRUCTURE AND STABILITY OF THE SIFN AND SIFN- SERIES, N = 1-5

The electronic and geometrical structure of the ground and low lying excited states of the SiF(n) and SiF- series (n = 1-5) are calculated within a local spin density approximation (LSDA) augmented with the nonlocal gradient corrections to the exchange functional. Energies of fragmentation through different decay channels, evaluated for both series, are in good accord with the experimental data and results of the post-Hartree-Fock (HF) calculations. The adiabatic electron affinity (EA(ad)) of all the title neutrals is estimated for the first time. The SiF4- anion is found to be stable towards dissociation and its neutral precursor possesses the near-zero EA(ad). The SiF5- anion is highly stable towards dissociation although stability of its neutral precursor, SiF5, is close to zero threshold. The intriguing peculiarity of the anions consists in nearly the same energy for the fluorine anion detachment that means an approximate equality of the affinity to F- for all the neutral silicon fluorides considered.