Ab Initio Density Functional Study on Negative Differential Resistance in a Fused Furan Trimer

We investigate the electronic transport properties of a trimer unit of cis-polyacetylene and a fused furan trimer using the ab initio density functional technique. Within the density functional theory, the effect of finite bias is introduced through nonequilibrium Green's functions. In the present study, both of the molecular systems have a thiol end group and they form a self-assembled monolayer on the Au (111) surface. The current−voltage characteristics of both the trimer unit of cis-polyacetylene and the fused furan trimer exhibit negative differential resistance over a certain range of bias voltage (±2.1 to ±2.45 V), and it is quite evident from the plot of differential conductance versus voltage. A detailed analysis of the origin of negative differential resistance has been given by observing the shift in transmission resonance peak across the bias window with varying bias voltage. The origin of the transmission resonance peak at certain bias voltages has been described from a study of molecular projected self-consistent Hamiltonian states.