Density functional theory: From fundamental precepts to nonlocal exchange- correlation functionals

Due to its favorable cost per unit accuracy, density functional theory (DFT) is the most popular quantum mechanical method for modeling the electronic structure of large molecules and complex materials. In DFT, the exchange-correlation functional has to be approximated since it's exact from is unknown. While commonly used functionals are often successful, they have large and systematic failures for certain types of molecules are properties. In this chapter, we review the fundamentals of DFT, with particular emphasis on exchange-correlation functionals and the role of the exchange-correlation hole in developing new functionals. After reviewing the failures of conventional approaches for developing functionals, we review our recent work to develop fully nonlocal functionals based on the uniform electron gas. © 2012 by Nova Science Publishers, Inc. All rights reserved.