title: Basis set convergence of the binding energies of strongly hydrogen-bonded atmospheric clusters.
abstract: We investigate the basis set convergence of second order Møller Plesset perturbation theory for the binding energies of 11 strongly hydrogen-bonded clusters relevant to the atmosphere. The binding energies are calculated both as the uncorrected (UC) value, as well as by employing the counterpoise (CP) and the Same Number Of Optimized Parameters (SNOOP) correction schemes, with and without explicit correlation (F12). We find that the use of the F12 corrections is of utter importance for obtaining converged binding energies. Without F12 corrections at least a quadruple-ζ basis set is generally required to yield errors below 1 kcal mol-1compared to the complete basis set (CBS) limit. Using coupled cluster methods we obtain a best estimate of the CCSD(T) CBS limit of the binding energies of the considered clusters and compare it with approximate DLPNO-CCSD(T) and DFT methods. We identify a pragmatic approach, relying solely on a series of double-ζ basis set calculations, for obtaining results in remarkably good agreement with our CBS estimate.
authors.affiliation: Division of Atmospheric Sciences, Department of Physics, University of Helsinki, Finland. jonas.elm@helsinki.fi.
authors.forename: Jonas
authors.initials: J
authors.lastname: Elm
authors.affiliation: qLEAP Center for Theoretical Chemistry, Department of Chemistry, Aarhus University, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Kristensen