A benchmark test suite for proton transfer energies and its use to test electronic structure model chemistries

Abstract

We present benchmark calculations of nine selected points on potential energy surfaces describing proton transfer process in three model systems, H5O2+, CH3OH…H+…OH2, and CH3COOH…OH2. The calculated relative energies of these geometries are compared to those calculated by various wave function and density functional methods, including the polarized molecular orbital (PMO) model recently developed in our research group and other semiempirical molecular orbital methods. We found that the SCC-DFTB and PMO methods (the latter available so far only for molecules consisting of only O and H and therefore only for the first of the three model systems) give results that are, on average, within 2 kcal/mol of the benchmark results. Other semiempirical molecular orbital methods have mean unsigned errors (MUEs) of 3 to 8 kcal/mol, local density functionals have MUEs in the range 0.7 to 3.7 kcal/mol, and hybrid density functionals have MUEs of only 0.3 to 1.0 kcal/mol, with the best density functional performance obtained by hybrid meta-GGAs, especially M06 and PW6B95.

Optimization of parameters for semiempirical methods VI: more modifications to the NDDO approximations and re-optimization of parameters

“…For thermochemistry, readily available collections of heats of formation for both gas and condensed phases include the JANAF [54], Lange’s handbook [55], CRC [56], and the NIST online WebBook [57]. Several reference data collections [16, 17, 37, 58] of high-quality calculated intermolecular interaction energies have been created in recent years, as have important and even more exotic quantities such as the heights of reaction barriers [32, 35]—again, as the result of high-quality calculations.…”

TD-DFT benchmarks: A review

“…As most compounds exhibiting interesting ES features are large conjugated molecules, the experimental works are often performed in condensed phase, making the simulation of environment a further problem for computational chemists. Therefore, contrary to GS properties, for which many standard benchmark sets have been designed (e.g., G3 for thermochemistry, S22 and S66 for weak‐interactions, ISO34 and ISO22 for isomerization energies, or sets for proton transfer, and GMTKN30 that gathers the majority of set developed for GS properties), a rather diverse palette of properties, training sets and calculation strategies have been proposed to evaluate the pros and cons of XCF within the TD‐DFT framework. As we will see in the following, this sometimes leads to nonuniform conclusions.…”

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

“…This low barrier suggests a very facile proton transfer step. However, from benchmark test studies for proton transfer energies, 89 it can be inferred that the barrier estimated with local density functionals of the GGA type is about 3 to 3.5 kcal mol -1 lower than that calculated with highly correlated ab initio methods. It should also be pointed out that since in our simulations the atoms are treated classically, the quantum effects associated with the proton motion are neglected.…”