Multiconfiguration Pair-Density Functional Theory

Kohn-Sham density functional theory with the available exchange-correlation functionals is less accurate for strongly correlated systems, which require a multiconfigurational description as a zero-order function, than for weakly correlated systems, and available functionals of the spin densities do not accurately predict energies for many strongly correlated systems when one uses multiconfigurational wave functions with spin symmetry. Furthermore, adding a correlation functional to a multiconfigurational reference energy can lead to double counting of electron correlation. Multiconfiguration pair-density functional theory (MC-PDFT) overcomes both obstacles, the second by calculating the quantum mechanical part of the electronic energy entirely by a functional, and the first by using a functional of the total density and the on-top pair density rather than the spin densities. This allows one to calculate the energy of strongly correlated systems efficiently with a pair-density functional and a suitable multiconfigurational reference function. This article reviewsMC-PDFT and related background information.

Automated summary

Kohn-Sham density functional theory is less accurate for strongly correlated systems compared to weakly correlated systems. The available functionals for spin densities do not accurately predict energies for strongly correlated systems when using multiconfigurational wave functions with spin symmetry. Multiconfiguration pair-density functional theory overcomes these limitations by using a functional of the total density and on-top pair density, allowing efficient calculation of energy for strongly correlated systems.