Mark E. Casida
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 Grenoble Cedex 9
It is proposed that the real objective of theory is not to obtain perfect agreement with experiment, but rather to obtain useful approximate solutions to idealized models. In so doing, I expect to take a slightly daring approach to presenting my own view of theoretical chemistry along with some review of the culture and folklore of quantum chemistry. I will try to apply this knowledge to give a broader picture of the intimate interrelationship between theory and approximations in density-functional theory (DFT) and time-dependent (TD) DFT and, I hope, convince the audience that getting good agreement with experiment using approximations with no theoretical basis at all is, at best, a questionable practice.