Assessing Many-Body Effects of Water Self-Ions. II: H₃O⁺(H₂O)_n Clusters

Abstract

The importance of many-body effects in the hydration of the hydronium ion (H3O+) is investigated through a systematic analysis of the many-body expansion of the interaction energy carried out at the coupled-cluster level of theory for the low-lying isomers of H3O+(H2O) n clusters with n = 1–5. This is accomplished by partitioning individual fragments extracted from the whole clusters into “groups” that are classified by both the number of H3O+ and water molecules and the hydrogen-bonding connectivity within a given fragment. Effects due to the presence of the Zundel ion, (H5O2)+, are analyzed by further partitioning fragment groups by the “context” of their parent clusters. With the aid of the absolutely localized molecular orbital energy decomposition analysis (ALMO EDA), this structure-based partitioning is found to largely correlate with the character of different many-body interactions, such as cooperative and anticooperative hydrogen bonding, within each fragment. This analysis emphasizes the importance of a many-body representation of inductive electrostatics and charge transfer in modeling the hydration of an excess proton in water. The comparison between the reference coupled-cluster many-body interaction terms with the corresponding values obtained with various exchange-correlation functionals demonstrates that many of these functionals yield an unbalanced treatment of the H3O+(H2O) n configuration space.

MB-Fit: Software Infrastructure for Data-Driven Many-Body Potential Energy Functions

“…[124][125][126] Because it is currently not possible to perform CM5 and XDM calculations at the DF-FNO-CCSD(T) level of theory, in order to guarantee the same representations of V pol , V 2B disp , and V elec for the two sets of TTM-nrg and MB-nrg PEFs, the CM5 and XDM calculations for all MB-PEFs were carried out with the ωB97M-V functional since it was shown to consistently provide the closest agreement with CCSD(T) data for various molecular interactions. 57,93,96,[138][139][140][141] Both the CM5 and XDM calculations were carried out with Q-Chem v5.1 121 using the aug-cc-pVTZ 137 basis set. All 1B and 2B energies were calculated using Psi4 122 at the corresponding QM level of theory, including counterpoise correction for the BSSE.…”

MB-Fit: Software Infrastructure for Data-Driven Many-Body Potential Energy Functions

“…[124][125][126] Because it is currently not possible to perform CM5 and XDM calculations at the DF-FNO-CCSD(T) level of theory, in order to guarantee the same representations of V pol , V 2B disp , and V elec for the two sets of TTM-nrg and MB-nrg PEFs, the CM5 and XDM calculations for all MB-PEFs were carried out with the ωB97M-V functional since it was shown to consistently provide the closest agreement with CCSD(T) data for various molecular interactions. 57,93,96,[138][139][140][141] Both the CM5 and XDM calculations were carried out with Q-Chem v5.1 121 using the aug-cc-pVTZ 137 basis set. All 1B and 2B energies were calculated using Psi4 122 at the corresponding QM level of theory, including counterpoise correction for the BSSE.…”

Manifolds of low energy structures for a magic number of hydrated sulfate: SO42−(H2O)24

“…24,[30][31][32][33][34] The quality of the force field has an influence on the relative energies of the various isomers in such non-covalent systems and polarization effects have been included to improve energetics. [34][35][36][37] The TTM2.1-F and TTM3-F flexible polarizable potentials have been developed to reproduce accurately infrared spectra of liquid water and ice by improving the description of the hydrogen bond network. 34 This force field family has been used to reproduce accurately the structures and spectroscopic features of large water clusters (from 20 to 400) and protonated water clusters with 20 molecules.…”