I hope you guys can help me understand these concepts better, did'nt find so much on google. This is from an old exam, Im preparing for my exam and I feel that I need to have an simple understatement of these. Thanks a lot! 1. The problem statement, all variables and given/known data Explain the following concepts and abbreviations in a concise manner. Also make relevant comments on how the concepts relate to DFT and HF ”SCF” ”Slater determinant” ”Exchange energy” ”Correlation energy” ”Self-interaction error” “Post Hartree-Fock methods” “PW91” “BO approximation” 2. Relevant equations 3. The attempt at a solution SCF - SCF is an iterative method that selects an approximate Hamiltonian, which solves the Schrödinger equation to get a more accurate set of orbits, and then resolves the Schrödinger equation with theses until the results coincide. SCF is used to study the electronic structure of atoms with more than one electron. The HF approximation is also known as an SCF method. Slater determinant - is what is called a determinant of spin orbital and is a way of writing wave functions to easily generate wave functions that are antisymmetric. A Slater determinant is a representation of a multi-part wave function for a system of fermions that meet the requirements for antisymmetry. In other words, the wave function changes the sign of the exchange of two particle coordinates. Exchange energy - It's the energy released when two or more electrons with the same spin change their positions in degenerate orbits. This term is not a feature of a given wave function or Hamiltonian. But within the Hartree-Fock and Kohn-Sham theories, it has clear meanings, namely, the energy contribution to the total energy due to the exchange of HF.