Event Description
John P. Perdew, PhD, Laura H. Carnell Professor of Physics and Chemistry, Temple University Kohn-Sham density functional theory is the most widely-used method of electronic-structure calculation in materials physics and chemistry, because it reduces the many-electron ground-state problem to a computationally tractable self-consistent one-electron problem. Exact in principle, it requires in practice an approximation to the density functional for the exchange-correlation energy. Common approximations fall on one of the five rungs of a ladder, with higher rungs being more complicated to construct but potentially more accurate. The first three or semi-local rungs are important, because (a) they are computationally efficient, (b) they can be constructed non-empirically, and (c) they can serve as input to fourth-rung hybrid functionals. The third-rung meta-generalized gradient approximation can recognize and describe covalent, metallic, and weak bonds, providing a good description of the equilibrium properties of many molecules and solids. |
