Density-functional calculations for large systems: can GGA functionals be competitive with hybrid functionals?

Two recently proposed correlation functionals, TCA and RevTCA, belonging to the generalized-gradient approximation (GGA) class, are briefly presented and their performances are discussed. The emphasis is put on the comparison with hybrid functionals, which are often the preferred ones for applications to molecular (but not to solid-state) systems. We show that the TCA and RevTCA performances are not far from those of hybrid functionals such as B3LYP or PBE0 when standard tests are performed and can be even better when less standard systems are considered. This is particularly interesting in view of applications to nano-scale systems or systems of biological interest, and, in general, in all the cases where the computer time requirements become an important constraint.