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 compared 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.

What Is Required for Highly Oxidized Molecules To Form Clusters with Sulfuric Acid?

“…We find that DLPNO-CCSD(T)/aug-cc-pVTZ yield a good agreement with the CCSD(T)-F12a/VDZ-F12 results, with a mean absolute error (MAE) of 0.2 kcal/mol and a maximum error of 0.8 kcal/mol. This is in good agreement with previous benchmark calculations on atmospheric mono/diamines 70 as well as a test set of 11 atmospheric cluster reactions 53. Hence we will use DLPNO-CCSD(T)/aug-cc-pVTZ for calculations on larger sulfuric acid -carboxylic acid clusters.…”

Effects of water, ammonia and formic acid on HO2 + Cl reactions under atmospheric conditions: competition between a stepwise route and one elementary step

“…46 The nal energies were obtained by performing single-point energy calculations at the CCSD(T)-F12A/VDZ-F12 (ref. [47][48][49] level of theory, based on the optimized geometries at the M06-2X/6-311++G(2d,2p) level, using ORCA. 50 It should be noted that the HO 2 + Cl reaction is a radical-radical reaction.…”

Effect of NH3 and HCOOH on the H2O2 + HO → HO2 + H2O reaction in the troposphere: competition between the one-step and stepwise mechanisms

“…To improve the accuracy of the energetics, using M06-2X/augcc-pVTZ optimized geometries, single-point energy was calculated using ORCA 42 at the CCSD(T)-F12a/cc-pVDZ-F12 level, [43][44][45] and the scaled ZPEs were added to them. The scaling factor employed to adjust the ZPEs was 0.9490.…”