Density Functional Theory of Electronic Structure

W. Kohn, A. D. Becke, R. G. Parr
1996 The Journal of Physical Chemistry  
Density functional theory (DFT) is a (in principle exact) theory of electronic structure, based on the electron density distribution n(r), instead of the many-electron wave function Ψ(r 1 ,r 2 ,r 3 ,...). Having been widely used for over 30 years by physicists working on the electronic structure of solids, surfaces, defects, etc., it has more recently also become popular with theoretical and computational chemists. The present article is directed at the chemical community. It aims to convey the
more » ... basic concepts and breadth of applications: the current status and trends of approximation methods (local density and generalized gradient approximations, hybrid methods) and the new light which DFT has been shedding on important concepts like electronegativity, hardness, and chemical reactivity index. Since n(r) also determines N by integration, it determines the full Hamiltonian H and thence, implicitly, all properties determined by H. Examples are the full N-particle ground state wave function Ψ(r 1 ,...,r N ), the electrical polarizability, the nth excitation energy, vibrational force constants, and potential energy surfaces for chemical reactions. With the help of this lemma, a minimal principle for the energy as functional of n(r) can be derived. 3 For given V(r) one defines the following energy functional of n(r): where is a functional of n(r), since Ψ is. 4 The minimal principle is
doi:10.1021/jp960669l fatcat:btzd3ghiirdwfmt4qnct7yki4m