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Applications and development of generalized dielectric boundary conditions to solvated systems in bulk water and air/water interface

Paul, Suranjan Kumar
http://orcid.org/0000-0002-1154-3065
http://rave.ohiolink.edu/etdc/view?acc_num=osu1669095139207493

Abstract Details

2022, Doctor of Philosophy, Ohio State University, Chemistry.
In the following thesis work, we have studied the applications of the Poisson equation (PEq) solver and attempted to develop its efficiency to study electronic structure of solvated systems in bulk and air/water interface. Contrary to polarizable continuum models (PCM), the PEq solver was designed to estimate the electrostatic solvation energy in anisotropic dielectric environments. We devised a systematic protocol to simulate vertical ionization energies (VIEs) for inorganic ions solvated in bulk and at the air/water interface using the PEq solver and compared them experimental results obtained using liquid microjet photoelectron spectroscopy. We chose an array of inorganic ions, some of which shows surface activity and are important to atmospheric chemistry and performed molecular dynamics simulations under periodic boundary conditions in bulk water and air/water interface, before computing the solvation energies using PEq solver. Surprising similarities between the computed VIEs at the bulk and air/water interface were observed. Further investigation helped us realize that this resemblance was due to the similarity of hydrogen-bonding network of the solvated ions in both the environments. This answered a vital question in relation to the experimental reports with regards to surface-sensitivity. Our results helped conclude that liquid microjet methods may be surface-sensitive, but the observable that it measures is not. We also implemented a generalized cavity construction routine in PEq solver that was applied to study the shielding e ects of embedded chromophores existing in dual, anisotropic solvated environment. The excitation energies of coumarin moieties were compared in bulk water and octa-acid/water environments. We concluded from this study that hydrophobic capsule shell formed by the octa-acid dimer shields the coumarins from external solvent, and the blue-shift in the excitation energy is similar to what we obtain from the effect of just capsule dielectric. Dielectric cavity construction is a vital step in the estimation of solvent effects. The most commonly used cavities were constructed using molecular structure of the solutes, subjected often to empirical parameters. We adapted the self-consistent continuum solvation model and the solvent-aware interfaces that constructs a smooth and accurate dielectric based on the electronic density of the solute. This method was tested for small molecules and water clusters to obtain promising results, but requires further benchmarking for production purposes. Finally, we attempted to improve the effciency of the PEq solver. Due to its three-dimensional background and numerical interface, the current version of the solver is highly ineffcient in terms of computational duration, compared to everyday PCM methods. Computation of solute electronic potentials were found to be the bottleneck of the overall routine due to the use of high resolution grids. We planned to compute the potential in quadrature based grids and interpolate it to Cartesian grids where the Poisson's equation is solved numerically. Inverse distance weighted method was implemented initially, followed by multipole expansion and electric field interpolation in a local implicit manner. This was followed by the adaptation of the radial basis function (RBF) interpolation method. The RBF method works fairly well in the global domain for the nuclear region. However, work is still needed to be done to reduce the cost of calculation of interpolating weights.
John Herbert (Advisor)
Alex Sokolov (Committee Member)
Bern Kohler (Committee Member)
168 p.
Chemistry

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Citations

  • Paul, S. K. (2022). Applications and development of generalized dielectric boundary conditions to solvated systems in bulk water and air/water interface [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1669095139207493

    APA Style (7th edition)

  • Paul, Suranjan. Applications and development of generalized dielectric boundary conditions to solvated systems in bulk water and air/water interface. 2022. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1669095139207493.

    MLA Style (8th edition)

  • Paul, Suranjan. "Applications and development of generalized dielectric boundary conditions to solvated systems in bulk water and air/water interface." Doctoral dissertation, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1669095139207493

    Chicago Manual of Style (17th edition)

osu1669095139207493
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This open access ETD is published by The Ohio State University and OhioLINK.
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