An Introduction of Density Functional Theory and its Application

This article starts with a brief history and idea interpretation of the Density Functional Theory (DFT), and then explains more detailedly about the original thought of Hohenberg and Kohn and their first and second theorem of the DFT. Next, it also introduces a methodology to treat the calculation based on DFT, which is the Kohn-Sham method based on the Local Density Approximation (LDA) treatment for the exchange energy term. In the later part, this paper touches two examples, as an illustration of how to get the density distribution n(r) from the Hohenberg-Kohn energy FHK, and from this part it shows the derivation in a combination of DFT with the statistical mechanics.