Density functional theory (DFT) models are among the most transferable models for electronic, molecular and mechanical properties of solids, liquids and gases; however their numerical load is typically preventing solving systems with more than several 100 atoms. This limit is particularly problematic when solving molecules at interfaces or in liquid solvents with very irregular solvent molecule distributions. Modeling these systems requires a large number of solvent molecules to ensure the results are unaffected by the simulation domain boundaries.

In this work, we introduce a DFT-based method to predict energies of solute molecules in bulk solution and in various distances to solvent/air interfaces [1]. The solute and all solvent molecules (~1400 atoms) are explicitly considered, and their electrons solved self-consistently in density functional tight binding. The statistical nature of the solvent molecule distribution and their orientations is included with 100 solvent samples for each solute configuration. Rotations of the solute molecule at the solvent surface are found to critically change their reaction energy barriers. Changes in the molecular energies of protonated reactant and transition state for hydrazone reaction at the solvent/air interfaces are used to predict reaction acceleration factors at solvent/air interfaces. The predicted acceleration factors of up to 4 orders of magnitude at solvent surfaces compared to the bulk solvent are in agreement with recent experimental observations of reactions in solvent microdroplets [2].

The presented method can be applied on liquids, crystalline and irregular materials, as well as all their interfaces. Our method shows DFT-based calculations of molecules and their explicit environments are not only feasible, but required for reliable predictions of interfaces.

International Workshop on Computational Nanotechnology 2021 (IWCN)

1. Narendra, N et al. J. Pys. Chem. A 124, 24 (2020)
2. Yan, X et al, Angew. Chem. Int. Ed. 55, 42 (2016)

Researchers should cite this work as follows:

• Namita Narendra, Jessica Wang, James Charles, Tillmann Christoph Kubis (2021), "IWCN 2021: Density Functional Theory Modeling of Chemical Reactions at Interfaces," https://nanohub.org/resources/35271.

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1. chemistry
2. computational chemistry
3. computational electronics
4. density functional theory (DFT)
5. IWCN 2021
6. solvents