[en] Infrared spectrum and NMR chemical shifts of Si(CH₃)₂O double free radical were calculated employing density functional theory (DFT) with the basis sets 6-311 + G(2d, p). Excited states, dipole moment and energy of Si(CH₃)₂O double free radical were also calculated using time dependent density function theory (TD-DFT) with the same basis sets. It is found that the external electric field along the X, Y and Z axis affect differently on the excited states and other properties of Si(CH₃)₂O double free radical. (author)

[en] The ionization spectrum of sulfur dioxide has been successfully studied by using the symmetry-adapted-cluster configuration-interaction (SAC-CI) general-R and SD-R methods and the basis set correlation-consistent polarized valence triple-zeta (cc-pVTZ). The SAC-CI general-R method reproduces the experimental spectrum well for both the main peaks and the satellite peaks of ionization spectrum of SO₂. The sequence of ionic states corresponding to main peaks of SO₂ has been re-determined according to the SAC-CI conclusions and it is reordered as X-bar ²A₁, òB₂, B-bar ²A₂, C-bar ²B₁, D-bar ²A₁, Ē²B₂ and F-bar ²A₁. Besides, the equilibrium structures and adiabatic ionization potentials (AIPs) of ionic states of main peaks of SO₂ are calculated by using the SAC-CI SD-R method. (atomic and molecular physics)

[en] The possible geometrical and electronic structures of small Au_n (n=2-9) clusters are optimized by mean of density functional theory (DFT). The effects of electron correlation is included in these calculations. The ground state equilibrium geometries and the atomization energies of Au_n(n=2-9) clusters have been calculated. It is shown that the atomization energy per atom increases with the cluster size. The energy level distribution, the Fermi levels and HOMO-LUMO gaps are investigated. Meanwhile, the electron affinities (EAs) and the ionization potentials (IPs) are calculated. The results are in excellent agreement with those of experiment. The even-odd effects of Fermi energy levels, IPs and EAs with the cluster size are explained