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A systematic study on the geometric and electronic structures of ground-state silicon oxide clusters (Si n Om, where n, m = 1−8) has been performed using molecular orbital and density functional theories. We find that most of the structures contain planar or buckled ring units. Pendent silicon atoms bonded only to a single oxygen atom are found in silicon-rich clusters. Oxygen-rich clusters have perpendicular planar rings, while silicon monoxide like clusters usually form a large buckled ring. Structures made up of tetrahedrally bonded units are found only in two clusters. Furthermore, the energy gap and net charge distribution for clusters with different silicon:oxygen ratios have been calculated.

Persistent currents in small nonsuperconducting rings threaded by a magnetic flux are a manifestation of novel quantum effects in submicron systems. We present theoretical results for one-channel and multichannel systems concerning the dependence of the current amplitude on the number of channels and geometry, temperature, and degree of disorder. Inelastic scattering is considered for one-channel loops only. We also discuss the observability of the effect.

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