The Grimme‐D3 semi‐empirical dispersion energy correction has been implemented for the original effective fragment potential for water (EFP1), and for systems that contain water molecules described by both correlated
The influence of a solvent environment on direct non-covalent interactions between two molecules: A symmetry-adapted perturbation theory study of polarization tuning of π – π interactions by water
High-level quantum chemical computations have provided significant insight into the fundamental physical nature of non-covalent interactions. These studies have focused primarily on gas-phase computations of small van der Waals dimers; however, these interactions frequently take place in complex chemical environments, such as proteins, solutions, or solids. To better understand how the chemical environment affects non-covalent interactions, we have undertaken a quantum chemical study of π– π interactions in an aqueous solution, as exemplified by T-shaped benzene dimers surrounded by 28 or 50 explicit water molecules. We report interaction energies (IEs) using second-order Møller–Plesset perturbation theory, and we apply the intramolecular and functional-group partitioning extensions of symmetry-adapted perturbation theory (ISAPT and F-SAPT, respectively) to analyze how the solvent molecules tune the π– π interactions of the solute. For complexes containing neutral monomers, even 50 explicit waters (constituting a first and partial second solvation shell) change total SAPT IEs between the two solute molecules by only tenths of a kcal mol −1 , while significant changes of up to 3 kcal mol −1 of the electrostatic component are seen for the cationic pyridinium–benzene dimer. This difference between charged and neutral solutes is attributed to large non-additive three-body interactions within solvated ion-containing complexes. Overall, except for charged solutes, our quantum computations indicate that nearby solvent molecules cause very little “tuning” of the direct solute–solute interactions. This indicates that differences in binding energies between the gas phase and solution phase are primarily indirect effects of the competition between solute–solute and solute–solvent interactions.
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- Award ID(s):
- 1955940
- NSF-PAR ID:
- 10353744
- Date Published:
- Journal Name:
- The Journal of Chemical Physics
- Volume:
- 156
- Issue:
- 19
- ISSN:
- 0021-9606
- Page Range / eLocation ID:
- 194306
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ab initio quantum mechanical (QM) molecules and EFP1. Binding energies obtained with these EFP1‐D and QM/EFP1‐D methods were tested using 27 benchmark species, including neutral, protonated, deprotonated, and auto‐ionized water clusters and nine solute–water binary complexes. The EFP1‐D and QM/EFP1‐D binding energies are compared with those obtained using fully QM methods: second‐order perturbation theory, and coupled cluster theory, CCSD(T), at the complete basis set (CBS) limit. The results show that the EFP1‐D and QM/EFP1‐D binding energies are in good agreement with CCSD(T)/CBS binding energies with a mean absolute error of 5.9 kcal/mol for water clusters and 0.8 kcal/mol for solute–water binary complexes. © 2018 Wiley Periodicals, Inc. -
null (Ed.)Density functional theory (DFT) calculations were used to examine the binding strength of one and two methane molecule(s) with graphene (62 and 186 carbon atoms) and model systems of aromatic hydrocarbons (benzene, pyrene, and coronene). We explored different possibilities of binding modes of methane such as one, two, and three C-H interacting with small π-systems. Two methane molecules were considered to bind from the same as well as opposite sides of the plane of benzene and other πsystems including graphene models. Our results show that methane molecule prefers to bind with three C-H…π interactions with all the π-systems except benzene. The preference of tripod configuration of methane on the surface of graphene systems strongly agrees with the neutron diffraction experiment of methane on graphitized carbon black. The binding strength is almost doubled by increasing the number of methane molecules from one to two. Importantly, two methane molecules prefer to bind on the same side rather than opposite sides of the plane of graphene due to stabilizing CH…HC interactions between them in addition to six CH…π interactions. Interestingly, binding strength contributions from CH…HC interactions (approx. 0.4–0.5 kcal/mol) of two methane molecules on the surface are analogous to methane dimer complex free from the surface of graphene. C-H stretching frequency shifts, bond lengths, and binding distances support the presence of CH…HC interactions between two methane molecules. Structures of complexes, binding energies, and C-H stretching frequency shifts agree with available experimental datamore » « less
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Abstract Solvation effects profoundly influence the characteristics and behavior of chemical systems in liquid solutions. The interaction between solute and solvent molecules intricately impacts solubility, reactivity, stability, and various chemical processes. Continuum solvation models gained prominence in quantum chemistry by implicitly capturing these interactions and enabling efficient investigations of diverse chemical systems in solution. In comparison, continuum solvation models in condensed matter simulation are very recent. Among these, the self‐consistent continuum solvation (SCCS) and the soft‐sphere continuum solvation models (SSCS) have been among the first to be successfully parameterized and extended to model periodic systems in aqueous solutions and electrolytes. As most continuum approaches, these models depend on a number of parameters that are linked to experimental or theoretical properties of the solvent, or that can be tuned based on reference data. Here, we present a systematic parameterization of the SSCS model for over 100 nonaqueous solvents. We validate the model's efficacy across diverse solvent environments by leveraging experimental solvation‐free energies and partition coefficients from comprehensive databases. The average root means square error over all the solvents was calculated as 0.85 kcal/mol which is below the chemical accuracy (1 kcal/mol). Similarly to what has been reported by Hille et al. (
J. Chem. Phys. 2019 ,150 , 041710.) for the SCCS model, a single‐parameter model accurately reproduces experimental solvation energies, showcasing the transferability and predictive power of these continuum approaches. Our findings underscore the potential for a unified approach to predict solvation properties, paving the way for enhanced computational studies across various chemical environments. -
The need for a deep understanding of CO2 interactions with other mols. is significant given the importance of supercrit. CO2 (s.c.-CO2) as a green solvent, and interest in design of novel materials for CO2 capture and storage. Soly. of fluorinated compds. in s.c.-CO2 is generally higher than their hydrocarbon analogs and fluorination of hydrocarbon compds. improves "CO2-philicity". Although dissoln. of a compd. in s.c.-CO2 (or any solvent) is a complex process, much can be learned by systematic examn. of solute-solvent interactions as a function of solute mol. properties in dimers and other small clusters. In the present study, Fourier-transform microwave spectroscopy and Symmetry Adapted Perturbation Theory (SAPT) calcns. have been used to examine intermol. interactions between CO2 and a series of fluorinated ethylene mols. with varying degree and position of fluorination (1-3 F atoms). While 1-fluoro-, 1,1-difluoro- and 1,1,2-trifluoroethylene...CO2 complexes are planar (with two isomers obsd. for 1-fluoroethylene), cis-1,2-difluoroethylene...CO2 is nonplanar. Although lowest energy structures predicted by MP2/6-311++G(2d,2p) calcns. are not always in agreement with obsd. configurations, SAPT calcns. provide binding energies consistent with the obsd. structures. We are now extending these studies to trimers contg. one fluorinated ethylene with two CO2 "solvent" mols. in order to gain further insight into structural and energetic changes as a solvation shell is formed.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0087302
