  Conjugated molecules are materials which are widely studied and developed for
molecular electronic technologies focusing on single molecule devices. In this
paper we observed the molecular conductance of single molecule based on n
phenyl ring systems with linker thiol (Sulfur) anchored on Cu[111] contacts.
The non equilibrium Greens function (NEGF) implemented in density functional
tight binding (gDFTB) is used to investigate the transport properties. Our
result showed that, increase of the phenyl ring will decrease the HOMO LUMO
energy gap. However, the conductance is decrease. The energy level of the
molecule (isolated molecule) broadens and shifts after anchoring to the Cu[111]
contacts.
