Range‐separated multiconfigurational density functional theory methods

AbstractRange‐separated multiconfigurational density functional theory (RS MC‐DFT) rigorously combines density functional (DFT) and wavefunction (WFT) theories. This is achieved by partitioning of the electron interaction operator into long‐ and short‐range components and modeling them with WFT and DFT, respectively. In contrast to other methods, mixing wavefunctions with density functionals, RS MC‐DFT is free from electron correlation double counting. The general formulation of RS MC‐DFT allows for merging any ab initio approximation with density functionals. Implementations of RS MC‐DFT aim at increasing both versatility and accuracy of the underlying methods, while reducing the computational cost of the ab initio problem. Variants of the RS MC‐DFT approach can be divided into single‐determinant‐based range‐separated methods and range‐separated multideterminantal WFT methods. In these approaches the electron correlation energy is described both by a pertinent short‐range density functional and by the wavefunction theory. We review the short‐range functionals and correlated wavefunction theories employed in the framework of RS MC‐DFT. We discuss applications of the RS MC‐DFT methods to ground‐state properties of molecules and to noncovalent interactions. Time‐dependent linear‐response theory and direct approaches to excited states are also presented. For each area of applications, we assess advantages of RS MC‐DFT over conventional DFT and ab initio methods.This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods Electronic Structure Theory > Density Functional Theory