First-principles studies of the electronic structure of cyclopentene on Si(100)*

Small organic molecules on silicon surfaces are promising candidates for active elements in nanoelectronic devices. The interplay between electronic states of the molecule and the silicon surface can change the molecular HOMO-LUMO gap, as well as result in interesting transport properties that depend sensitively on the alignment of molecular frontier orbitals with the silicon band structure. In this work, we determine this alignment quantitatively using the GW method for cyclopentene on Si(100), a prototypical organic-molecule/silicon junction of interest in molecular electronics. We will discuss our results in the context of recent STM experiments that observed negative differential resistance in this system.