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Common approximations in Density Functional Theory

Authors: Micael Oliveira

Ref.: 9th ETSF Young Researchers Meeting, Brussels, Belgium, May 21-25 (2012)

Abstract: Density functional theory (DFT) is one of the most successful theories in Physics and Chemistry of the last decades and it is used to predict a wide variety of properties of atoms, molecules, and solids. Although in principle it is an exact theory, for practical applications several approximations are required within the theory. The most obvious of these approximations is the choice of the exchange and correlation functional used. Indeed, the exact exchange and correlation functional is unknown and needs to be approximated, which can have a great impact on the accuracy of the results. Other approximations are made because they are convenient. One example of such approximation is the use of pseudopotentials, were the core electrons of the atoms are replaced by an effective potential that accounts for the nuclear attraction and all the interactions between the valence and the inert inner core electrons. In this talk we will discuss several common approximations in DFT, how they can affect the electronic properties of various systems, and what can be done to try to keep them under control.