The theory of currents through small bridge molecules

A model to treat the theory of currents through small bridge molecules connected to leads is constructed using the time-dependent Schrodinger equation and the wide-band approximation to treat the leads. It is shown that the behaviour of the current through the bridge may be summarized by considering three time periods: a transient period, a quasi-steady -state period and a decaying period. The results obtained are compared with previous work and in particular it is shown that, under reasonable assumptions, they are in accord with the more conventional time-independent scattering theory approaches in the steady-state period. Illustrative calculations are presented for both chain and ring bridge molecules. (c) 2007 Wiley Periodicals, Inc.