Virtual Winter School on Computational Chemistry
More items are visible when logged in!
31 video lectures on Density Functional Theory.
Density Functional Theory (DFT) is the choice method of calculating quantum chemistry today. Here, we've assembled many review articles from our group as well as the ABC of DFT.
Evert Jan Baerends
Theoretical Chemistry,Vrije Universiteit, Amsterdam, The Netherlands
We will first review many wrong statements in the literature on the nature and the (lack of) physical meaning of Kohn-Sham orbitals. Next the nature of the occupied KS orbitals, and their advantages over Hartree-Fock orbitals are highlighted.Then we address orbital energies. Exact KS orbitals have many virtues:
Unfortunately, orbital energies in the common LDA and GGA calculations are very wrong: they are typically 5 eV (more than 100 kcal/mol) higher than the exact Kohn-Sham orbital energies, an error that would be completely unacceptable in total energies. We will first analyze where this error comes from - it is not due to wrong asymptotic behavior of LDA/GGA potentials, or to a “self-interaction error” but it is caused by erroneous density dependence of the standard Exc[ρ] functionals, hence a wrong derivative (= potential). We will demonstrate that approximate potentials can be formulated that have similar good properties for ionization and excitation energies as the exact KS potential .
Mark E. Casida
Professeur, chimie théorique, Laboratoire de Chimie Inorganique REdox (CIRE),Département de Chimie Moléculare (DCM, UMR CNRS/UGA 5250), Institut de Chimie Moléculaire de Grenoble(ICMG, FR-2607), Université Grenoble Alpes, 301 rue de la Chimie, CS 40700, 38058 GrenobleCedex 9, FRANCE.
Ordinary density-functional theory (DFT) is restricted to calculating the static electronic energy and density of the electronic ground state. Time-dependent (TD) DFT is a parallel formalism whichallows us to extend the power of DFT to treat time-dependent perturbations. Time-dependent response theory then allows us to calculate absorption spectra from TD-DFT and hence to treat excited states. This formalism is explained at the level of a Masters student, first by setting the stage with a reminder of simple wave function theory for excited states as well as some more advanced ab initio quantum chemistry ideas, and then by focusing on TD-DFT. Some illustrative examples are also presented 1,2 . We also direct the interested reader to highly-cited review articles, including our own 3,4 .
Site made with by