title: Communication: rationale for a new class of double-hybrid approximations in density-functional theory.
abstract: We provide a rationale for a new class of double-hybrid approximations introduced by Brémond and Adamo [J. Chem. Phys. 135, 024106 (2011)] which combine an exchange-correlation density functional with Hartree-Fock exchange weighted by λ and second-order Møller-Plesset (MP2) correlation weighted by λ(3). We show that this double-hybrid model can be understood in the context of the density-scaled double-hybrid model proposed by Sharkas et al. [J. Chem. Phys. 134, 064113 (2011)], as approximating the density-scaled correlation functional E(c)[n(1/λ)] by a linear function of λ, interpolating between MP2 at λ = 0 and a density-functional approximation at λ = 1. Numerical results obtained with the Perdew-Burke-Ernzerhof density functional confirms the relevance of this double-hybrid model.
authors.affiliation: Laboratoire de Chimie Théorique, Université Pierre et Marie Curie and CNRS, 75005 Paris, France. julien.toulouse@upmc.fr
authors.forename: Julien
authors.initials: J
authors.lastname: Toulouse
authors.forename: Kamal
authors.initials: K
authors.lastname: Sharkas
authors.forename: Eric
authors.initials: E
authors.lastname: Brémond
authors.forename: Carlo
authors.initials: C
authors.lastname: Adamo
mesh_terms: D008956:Models, Chemical; D011789:Quantum Theory