Assessment and formal properties of exchange-correlation functionals constructed from the adiabatic connection.

We examine the development and investigate the performance of exchange-correlation functionals constructed from the adiabatic connection. Our method is based on a direct modeling of the adiabatic connection curve in the coupling-constant space and is very flexible in the models. Several different models are investigated in the construction of new families of exchange-correlation functionals. Also the performance of two of these models (MCY1 and MCY2) is investigated over a wider range of systems and properties, with comparison made to the performance of established functionals. Overall, the adiabatic functionals improve upon widely used hybrid and generalized gradient approximation functionals, particularly in correctly describing one-electron systems and reaction energy barriers.