5 research outputs found
Hohenberg-Kohn-Sham density functional theory
The emergence of a family of computational methods, known under the label âdensity functional theoryâdex theory! density functional ' or âDFT', revolutionalized the field of computer modelling of complex molecular systems. Many computational schemes belonging to the DFT family are currently in use. Some of them are designed to be universal (nonempirical) whereas other to treat specific systems and/or properties (empirical). This review starts with the introduction of the formal elements underlying all these methods: Hohenberg-Kohn theoremsâdex theorem! Hohenberg-Kohn, reference systemâdex reference system of noninteracting electronsâdex reference system! noninteracting electrons, exchange-correlation energyâdex energy functional! exchange-correlation functionalâdex functional, and the Kohn-Sham equationsâdex equation! Kohn-Sham. The main roads to approximate the exchange-correlation-energy functional based on: local density approximationâdex approximation! local density (LDA), generalized gradient approximationâdex approximation! generalized gradient (GGA), meta-GGAâdex energy functional! exchange-correlation! meta-GGA, and adiabatic connectionâdex adiabatic connection formula (hybrid functionalsâdex energy functional! exchange-correlation! hybrid ), are outlined. The performance of these approximations in describing molecular properties of relevance to intermolecular interactionâdex interactions! intermolecular s and their interactions with environment in condensed phase (ionization potentialâdex potential! ionization s, electronâdex electron affinitiesâdex electron! affinity, electric momentsâdex electric moment, polarizabilitiesâdex polarizability ) is reviewed. Developments concerning new methods situated within the general Hohenberg-Kohn-Sham framework or closely related to it are overviewed in the last sectio