Modeling level alignment at interfaces in molecular junctions

Molecular devices are planned as alternative solutions for heat dissipation problems and reliable fabrication of nano-scale devices. However, it also opens up possibilities of combining many other degrees of freedom into functional device design. While they introduce interesting opportunities for study, they also demand a versatile, scalable toolset. In this thesis we calculate the electronic transport through molecular devices using the DFT+NEGF technique. We model the interaction of the molecule with the electrodes surfaces taking into account different facts such as the gap reduction produced by the charge polarization on metallic surfaces, the spin states of the molecule and the hydrophilicity of the leads. We hope our contribution helps to improve the functional single molecule devices design.QN/Thijssen Grou

Transport gap renormalization at a metal-molecule interface using DFT-NEGF and spin unrestricted calculations

A method is presented for predicting one-particle energies for a molecule in a junction with one metal electrode, using density functional theory methods. In contrast to previous studies, in which restricted spin configurations were analyzed, we take spin polarization into account. Furthermore, in addition to junctions in which the molecule is weakly coupled, our method is also capable of describing junctions in which the molecule is chemisorbed to the metal contact. We implemented a fully self-consistent scissor operator to correct the highest occupied molecular orbital-lowest unoccupied molecular orbital gap in transport calculations for single molecule junctions. We present results for various systems and compare our results with those obtained by other groups.QN/Thijssen Grou