First-principles studies of the electronic structure ofcyclopentene on Si(001): density functional theory and GWcalculations

Description/Abstract

The electronic structure and ground-state geometry of cyclopentene monolayers on Si(001) are studied using ab initio pseudopotential density-functional theory (DFT). Quasiparticle excitation spectra are calculated within the GW approximation. Both cis and transcyclopentene monolayers are considered. In both geometries, a strong electronic coupling between the monolayer and Si substrate is found; substantial inter-molecular interactions are present, as indicated by broadening in molecular levels that are decoupled from the substrate. It is argued that the cis structure is kinetically favored, and we evaluate self-energy corrections to the eigenstates of this configuration near the band edges within the GW approximation. The calculated self-energy corrections are large, exceeding those of bulk Si, and increase the energy gap between occupied and unoccupied frontier adsorbate states by 1.3 eV.