Aligning Fermi Levels for the Tutorial ”Hands on Simulations of Interfacial Electron Transfer”

In this extension of the main IET tutorial, we will deal with the mis-alignment issue that is inherent in Extended Hückel (EH) theory. In such method, the energies of states in different materials are parametrized differently. As a result, the position of the Fermi levels (EF ) of different materials are not referenced to the same vacuum energy. [1] This causes an issue in that a supercell containing different materials will have mis-aligned molecular states. Here we describe a patch fix for this problem, based on the original code of YAEHMOP. Because the IET code also uses YAEHMOP to perform electronic structure calculations, this implementation works for the IET code as well. We will first look at the theory behind this EF alignment. Then, the implementation in the YAEHMOP code will be introduced together with the explanation and usage of new keyword options. Finally an example will be discussed to show how this implementation helps us in electronic structure calculations with Extended Hückel theory. As in the main IET tutorial, colored text indicates links that can be clicked on.