Software and Tools for Density Functional Theory

Density functional theory represents a revolution in the description of electronic structure in materials, molecules, and complex systems. The aim of the present chapter is to introduce the reader to DFT software-indispensable tools to unlock the power of this theoretical framework. First, an overview will be given about some of the freely available packages—quantum ESPRESSO, OpenMX, Yambo, among others—and commercial ones like Gaussian, ADF, and VASP-together with their strengths, weaknesses, and applicability to material science and biological systems. Then, it will be shown in a tutorial how to perform a basic DFT calculation step by step: it will be shown how to define the system, how to take into account possible high-performance computing, how to choose functional and basis sets, and how to analyze the output. This tutorial will provide the reader with the background needed to use DFT codes for research purposes with the help of visualization tools. The chapter allows the reader to connect what has been shown so far to the actual practice and use of DFT software.