Towards adiabatic-connection interpolation model with broader applicability

The adiabatic connection integrand interpolation (ACII) method represents a general path for calculating correlation energies in electronic systems within the density functional theory. ACII functionals include both exact-exchange and the second-order correlation energy, as well as an interpolating function toward the strictly correlated electron (SCE) regime. Several interpolating functions have been proposed in the last years targeting different properties, yet an accurate ACII approach with broad applicability is still missing. Recently, we have proposed an ACII functional that was made accurate for the three-dimensional (3D) uniform electron gas as well as for model metal clusters. In this paper we present an ACII functional (named genISI2), which is very accurate for both three-dimensional (3D) and two-dimensional (2D) uniform electron gases and for the quasi-2D infinite-barrier model, where most of the exchange-correlation functionals fail badly, as well as for strongly correlated two-electrons systems. Using the exact-exchange Kohn-Sham orbitals, we have also assessed the genISI2 for various molecular systems, showing a superior performance with respect to the other ACII methods for total energies, atomization energies, and ionization potentials. The genISI2 functional can thus find application in a broad range of systems and properties.