First Principles Investigations Of The Transport Properties Of Fe-c Clusters

First-principles calculations based on combination of Density Functional Theory and Non-equilibrium Green Function have been performed to study several problems about transport properties in FeC_n and Fe₂C_n cluster.Including equilibrium cond- uctance,eigenchannels,charge-transfer doping,I-V characteristics. Inaddition , We compare FeC_n and Fe₂C_n cluster with C chain'characteristicsIn chapter three, we have performed first-principles calculations on the transport properties of FeC_n and Fe₂C_n (n=1⁶) clusters coupled with two Al(100) electrodes based on a recently developed ab-initio non-equilibrium Green's function formalism. .our result show that equilibrium conductance of the two above system show oscillation behavior from n=3,n=1, with an amplitude of oscillation about 0.1 G0. The transmission spectra of these two kinds of clusters show similar character. As the increase of the carbon atoms, their transmission spectra development show similar trend When n=3, the total transmission spectra is determined totally by two degenerate eigenchannels. In particular, FeC3 and FeC4 clusters also displays a negative transconductance behavior for a small fixed drain bias.