Electron scattering processes in steroid molecules via NEGF-DFT: The opening of conduction channels by central oxygen.

We present a careful analysis of the electron transport in a variety of steroid derivatives attached among Au (111) electrodes. Our discussion is based on the non-equilibrium Green's function formalism coupled to the density functional theory, as well as appropriate parameters, such as the current-voltage behavior, differential conductance, rectification ratio, transmittance, the projected density of states, and the corresponding eigenchannels. The systems investigated present antagonistic features. While the cholesterol has no appreciable electrical rectification and works as an insulator, cortisol presents an evident diode-like behavior with an intense micro-ampere current with a strong peak at ca. 0.3 eV. This characteristic is a consequence of the systematic remotion of saturated carbon chains, and the inclusion of oxygen atoms. These results can help to understand biological processes involving these molecules besides designing new devices for applications in molecular electronics.