Geometry, chemical bonding, and electronic spectra of [Si.sub.n] and [Si.sub.n]-glycine (n = 3-5) complexes

The geometry, chemical bonding and the electronic excitations of [Si.sub.n] and [Si.sub.n]-glycine (Gly) (n = 3-5) complexes are calculated as a potential model of an inorganic cluster-biomolecule system, focusing on the effects of the [Si.sub.n]-Gly interactions on the structures of Gly and on the electronic transitions of [Si.sub.n]. The interactions with Gly are predicted to shift the electronic excitation energies of [Si.sub.n] to the blue from to 2.1-2.7 eV.