Journal of computational methods in sciences and engineering
Paginering:
Jaargang 7 (2008) nr. 3-4 pagina's 257-272
Jaar:
2008-04-28
Inhoud:
The structural, electronic, dynamical and spectral properties of Si_{6} and its ions (Si_{6}^{1-}, Si_{6}^{2-}, and Si_{6}^{1+}) have been examined using a variety of high level ab initio techniques, including quadratic configuration interaction, coupled cluster, and density functional theory (DFT) with the hybrid B3LYP functional. Various high quality correlation-consistent basis sets, ranging from 2Z up to 5Z quality, were employed for the DFT calculations. It is shown that not only the ground state structure, but also the structure of the excited states, as well as the structure of the anions and cations of Si_{6} are controversial. Each one of the three competing structures for the ground state, with C_{s}/C_{2v}, D_{4h}, and C_{2v} symmetry, has been considered by different investigators as the lowest energy structure either of the neutral cluster, or of its anion or cation (or both). In a spirit of "structural democracy" it is demonstrated that the C_{s}/C_{2v}, D_{4h}, and _{2v} structures can be safely assigned as the ground states of the neutral, anion, and cation clusters respectively. The present results, which support the structural plasticity (fluxionality) of Si_{6}, are in excellent agreement with experiment, including Raman and IR spectra, ionization energies, electron affinities as well as vibrationally resolved photoelectron spectra. The paradigm of Si_{6} could be very helpful for other silicon clusters as well.
Tijdschrift beschrijving