title: Assessing the Performance of CASPT2 and DFT Methods for the Description of Long, Multicenter Bonding in Dimers between Radical Ions.
abstract: The performance of a wide variety of density functionals for the description of long, multicenter bonding in dimers between radical ions has been addressed in this work. Results on interaction energies and equilibrium distances have been evaluated through pure GGA and meta-GGA, hybrid, RSH, and double hybrid functionals. Grimme's dispersion corrections have also been assessed. All results are systematically analyzed and compared for the π-[TCNE]2(2-), π-[TTF]2(2+), π-[TCNB]2(2-), and π-[TCNP]2(2-) dimers. The DFT results are benchmarked against RASPT2 calculations based on large active spaces. It is shown that small active spaces do not quantitatively describe the interaction energy curves of these dimers. B97-D3(BJ) turns to be the functional that best reproduces the finest RASPT2 results, while PBE-D3(BJ), B3LYP-D3(BJ), and M06-L also provide satisfactory results.
authors.affiliation: Departament de Química Física and IQTCUB, Facultat de Química, Universitat de Barcelona , Av. Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Marçal
authors.initials: M
authors.lastname: Capdevila-Cortada
authors.affiliation: Departament de Química Física and IQTCUB, Facultat de Química, Universitat de Barcelona , Av. Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Ribas-Arino
authors.affiliation: Departament de Química Física and IQTCUB, Facultat de Química, Universitat de Barcelona , Av. Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Novoa