ABSTRACT

Number of Electrons ................................................................................ 541 34.3 Approximate Expressions for Local Functionals..................................... 545 34.4 Computation of Chemical Potential and Hardness.................................. 547 34.5 Computation of the Fukui Function for a Nucleophilic Attack fþ(r) ..... 550 34.6 Conclusions.............................................................................................. 558 Acknowledgments................................................................................................. 559 Notes and References............................................................................................ 559

Density functional theory (DFT) uses the electron density r(r) as the basic source of information of an atomic or molecular system instead of the many-electron wave function [1-7]. The theory is based on the Hohenberg-Kohn theorems, which establish the one-to-one correspondence between the ground state electron density of the system and the external potential v(r) (for an isolated system, this is the potential due to the nuclei) [6]. The electron density uniquely determines the number of electrons N of the system [6]. These theorems also provide a variational principle, stating that the exact ground state electron density minimizes the exact energy functional E[r(r)].