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Celia Fonseca Guerra - One of the best experts on this subject based on the ideXlab platform.

  • secondary Electrostatic Interaction model revised prediction comes mainly from measuring charge accumulation in hydrogen bonded monomers
    Journal of the American Chemical Society, 2019
    Co-Authors: Stephanie C C Van Der Lubbe, Francesco Zaccaria, Xiaobo Sun, Celia Fonseca Guerra
    Abstract:

    The secondary Electrostatic Interaction (SEI) model is often used to predict and explain relative hydrogen bond strengths of self-assembled systems. The SEI model oversimplifies the hydrogen-bonding mechanisms by viewing them as interacting point charges, but nevertheless experimental binding strengths are often in line with the model’s predictions. To understand how this rudimentary model can be predictive, we computationally studied two tautomeric quadruple hydrogen-bonded systems, DDAA-AADD and DADA-ADAD. Our results reveal that when the proton donors D (which are electron-donating) and the proton acceptors A (which are electron-withdrawing) are grouped together as in DDAA, there is a larger accumulation of charge around the frontier atoms than when the proton donor and acceptor groups are alternating as in DADA. This accumulation of charge makes the proton donors more positive and the proton acceptors more negative, which enhances both the Electrostatic and covalent Interactions in the DDAA dimer. The...

Markus Bier - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatic Interaction of particles trapped at fluid interfaces: effects of geometry and wetting properties.
    Soft matter, 2018
    Co-Authors: Arghya Majee, Markus Bier, Siegfried Dietrich
    Abstract:

    The Electrostatic Interaction between pairs of spherical or macroscopically long, parallel cylindrical colloids trapped at fluid interfaces is studied theoretically for the case of small inter-particle separations. Starting from the effective Interaction between two planar walls and by using the Derjaguin approximation, we address the issue of how the Electrostatic Interaction between such particles is influenced by their curvatures and by the wetting contact angle at their surfaces. Regarding the influence of curvature, our findings suggest that the discrepancies between linear and nonlinear Poisson-Boltzmann theory, which have been noticed before for planar walls, also occur for spheres and macroscopically long, parallel cylinders, though their magnitude depends on the wetting contact angle. Concerning the influence of the wetting contact angle θ simple relations are obtained for equally sized particles which indicate that the inter-particle force varies significantly with θ only within an interval around 90°. This interval depends on the Debye length of the fluids and on the size of the particles but not on their shape. For unequally sized particles, a more complicated relation is obtained for the variation of the inter-particle force with the wetting contact angle.

  • Electrostatic Interaction of particles trapped at fluid interfaces effects of geometry and wetting properties
    arXiv: Soft Condensed Matter, 2018
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between pairs of spherical or macroscopically long, parallel cylindrical colloids trapped at fluid interfaces is studied theoretically for the case of small inter-particle separations. Starting from the effective Interaction between two planar walls and by using the Derjaguin approximation, we address the issue of how the Electrostatic Interaction between such particles is influenced by their curvatures and by the wetting contact angle at their surfaces. Regarding the influence of curvature, our findings suggest that the discrepancies between linear and nonlinear Poisson-Boltzmann theory, which have been noticed before for planar walls, also occur for spheres and macroscopically long, parallel cylinders, though their magnitude depends on the wetting contact angle. Concerning the influence of the wetting contact angle $\theta$ simple relations are obtained for equally sized particles which indicate that the inter-particle force varies significantly with $\theta$ only within an interval around $90^\circ$. This interval depends on the Debye length of the fluids and on the size of the particles but not on their shape. For unequally sized particles, a more complicated relation is obtained for the variation of the inter-particle force with the wetting contact angle.

  • Electrostatic Interaction between dissimilar colloids at fluid interfaces
    Physical Review E, 2018
    Co-Authors: Arghya Majee, Markus Bier, Timo Schmetzer
    Abstract:

    The Electrostatic Interaction between two nonidentical, moderately charged colloids situated in close proximity of each other at a fluid interface is studied. By resorting to a well-justified model system, this problem is analytically solved within the framework of linearized Poisson-Boltzmann density functional theory. The resulting Interaction comprises a surface and a line part, both of which, as functions of the interparticle separation, show a rich behavior including monotonic as well as nonmonotonic variations. In almost all cases, these variations cannot be captured correctly by using the superposition approximation. Moreover, expressions for the surface tensions, the line tensions and the fluid-fluid interfacial tension, which are all independent of the interparticle separation, are obtained. Our results are expected to be particularly useful for emulsions stabilized by oppositely charged particles.

  • Poisson-Boltzmann study of the effective Electrostatic Interaction between colloids at an electrolyte interface
    The Journal of Chemical Physics, 2016
    Co-Authors: Arghya Majee, Markus Bier, Siegfried Dietrich
    Abstract:

    The effective Electrostatic Interaction between a pair of colloids, both of them located close to each other at an electrolyte interface, is studied by employing the full, nonlinear Poisson-Boltzmann (PB) theory within classical density functional theory. Using a simplified yet appropriate model, all contributions to the effective Interaction are obtained exactly, albeit numerically. The comparison between our results and those obtained within linearized PB theory reveals that the latter overestimates these contributions significantly at short inter-particle separations. Whereas the surface contributions to the linear and the nonlinear PB results differ only quantitatively, the line contributions show qualitative differences at short separations. Moreover, a dependence of the line contribution on the solvation properties of the two adjacent fluids is found, which is absent within the linear theory. Our results are expected to enrich the understanding of effective interfacial Interactions between colloids.

  • Electrostatic Interaction between colloidal particles trapped at an electrolyte interface
    Journal of Chemical Physics, 2014
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between colloidal particles trapped at the interface between two immiscible electrolyte solutions is studied in the limit of small inter-particle distances. Within an appropriate model analytic expressions for the Electrostatic potential as well as for the surface and line Interaction energies are obtained. They demonstrate that the widely used superposition approximation, which is commonly applied to large distances between the colloidal particles, fails qualitatively at small distances, and is quantitatively unreliable even at large distances. Our results contribute to an improved description of the Interaction between colloidal particles trapped at fluid interfaces.

Arghya Majee - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatic Interaction of particles trapped at fluid interfaces: effects of geometry and wetting properties.
    Soft matter, 2018
    Co-Authors: Arghya Majee, Markus Bier, Siegfried Dietrich
    Abstract:

    The Electrostatic Interaction between pairs of spherical or macroscopically long, parallel cylindrical colloids trapped at fluid interfaces is studied theoretically for the case of small inter-particle separations. Starting from the effective Interaction between two planar walls and by using the Derjaguin approximation, we address the issue of how the Electrostatic Interaction between such particles is influenced by their curvatures and by the wetting contact angle at their surfaces. Regarding the influence of curvature, our findings suggest that the discrepancies between linear and nonlinear Poisson-Boltzmann theory, which have been noticed before for planar walls, also occur for spheres and macroscopically long, parallel cylinders, though their magnitude depends on the wetting contact angle. Concerning the influence of the wetting contact angle θ simple relations are obtained for equally sized particles which indicate that the inter-particle force varies significantly with θ only within an interval around 90°. This interval depends on the Debye length of the fluids and on the size of the particles but not on their shape. For unequally sized particles, a more complicated relation is obtained for the variation of the inter-particle force with the wetting contact angle.

  • Electrostatic Interaction of particles trapped at fluid interfaces effects of geometry and wetting properties
    arXiv: Soft Condensed Matter, 2018
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between pairs of spherical or macroscopically long, parallel cylindrical colloids trapped at fluid interfaces is studied theoretically for the case of small inter-particle separations. Starting from the effective Interaction between two planar walls and by using the Derjaguin approximation, we address the issue of how the Electrostatic Interaction between such particles is influenced by their curvatures and by the wetting contact angle at their surfaces. Regarding the influence of curvature, our findings suggest that the discrepancies between linear and nonlinear Poisson-Boltzmann theory, which have been noticed before for planar walls, also occur for spheres and macroscopically long, parallel cylinders, though their magnitude depends on the wetting contact angle. Concerning the influence of the wetting contact angle $\theta$ simple relations are obtained for equally sized particles which indicate that the inter-particle force varies significantly with $\theta$ only within an interval around $90^\circ$. This interval depends on the Debye length of the fluids and on the size of the particles but not on their shape. For unequally sized particles, a more complicated relation is obtained for the variation of the inter-particle force with the wetting contact angle.

  • Electrostatic Interaction between dissimilar colloids at fluid interfaces
    Physical Review E, 2018
    Co-Authors: Arghya Majee, Markus Bier, Timo Schmetzer
    Abstract:

    The Electrostatic Interaction between two nonidentical, moderately charged colloids situated in close proximity of each other at a fluid interface is studied. By resorting to a well-justified model system, this problem is analytically solved within the framework of linearized Poisson-Boltzmann density functional theory. The resulting Interaction comprises a surface and a line part, both of which, as functions of the interparticle separation, show a rich behavior including monotonic as well as nonmonotonic variations. In almost all cases, these variations cannot be captured correctly by using the superposition approximation. Moreover, expressions for the surface tensions, the line tensions and the fluid-fluid interfacial tension, which are all independent of the interparticle separation, are obtained. Our results are expected to be particularly useful for emulsions stabilized by oppositely charged particles.

  • Poisson-Boltzmann study of the effective Electrostatic Interaction between colloids at an electrolyte interface
    The Journal of Chemical Physics, 2016
    Co-Authors: Arghya Majee, Markus Bier, Siegfried Dietrich
    Abstract:

    The effective Electrostatic Interaction between a pair of colloids, both of them located close to each other at an electrolyte interface, is studied by employing the full, nonlinear Poisson-Boltzmann (PB) theory within classical density functional theory. Using a simplified yet appropriate model, all contributions to the effective Interaction are obtained exactly, albeit numerically. The comparison between our results and those obtained within linearized PB theory reveals that the latter overestimates these contributions significantly at short inter-particle separations. Whereas the surface contributions to the linear and the nonlinear PB results differ only quantitatively, the line contributions show qualitative differences at short separations. Moreover, a dependence of the line contribution on the solvation properties of the two adjacent fluids is found, which is absent within the linear theory. Our results are expected to enrich the understanding of effective interfacial Interactions between colloids.

  • Electrostatic Interaction between colloidal particles trapped at an electrolyte interface
    Journal of Chemical Physics, 2014
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between colloidal particles trapped at the interface between two immiscible electrolyte solutions is studied in the limit of small inter-particle distances. Within an appropriate model analytic expressions for the Electrostatic potential as well as for the surface and line Interaction energies are obtained. They demonstrate that the widely used superposition approximation, which is commonly applied to large distances between the colloidal particles, fails qualitatively at small distances, and is quantitatively unreliable even at large distances. Our results contribute to an improved description of the Interaction between colloidal particles trapped at fluid interfaces.

S Dietrich - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatic Interaction of particles trapped at fluid interfaces effects of geometry and wetting properties
    arXiv: Soft Condensed Matter, 2018
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between pairs of spherical or macroscopically long, parallel cylindrical colloids trapped at fluid interfaces is studied theoretically for the case of small inter-particle separations. Starting from the effective Interaction between two planar walls and by using the Derjaguin approximation, we address the issue of how the Electrostatic Interaction between such particles is influenced by their curvatures and by the wetting contact angle at their surfaces. Regarding the influence of curvature, our findings suggest that the discrepancies between linear and nonlinear Poisson-Boltzmann theory, which have been noticed before for planar walls, also occur for spheres and macroscopically long, parallel cylinders, though their magnitude depends on the wetting contact angle. Concerning the influence of the wetting contact angle $\theta$ simple relations are obtained for equally sized particles which indicate that the inter-particle force varies significantly with $\theta$ only within an interval around $90^\circ$. This interval depends on the Debye length of the fluids and on the size of the particles but not on their shape. For unequally sized particles, a more complicated relation is obtained for the variation of the inter-particle force with the wetting contact angle.

  • Electrostatic Interaction between colloidal particles trapped at an electrolyte interface
    Journal of Chemical Physics, 2014
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between colloidal particles trapped at the interface between two immiscible electrolyte solutions is studied in the limit of small inter-particle distances. Within an appropriate model analytic expressions for the Electrostatic potential as well as for the surface and line Interaction energies are obtained. They demonstrate that the widely used superposition approximation, which is commonly applied to large distances between the colloidal particles, fails qualitatively at small distances, and is quantitatively unreliable even at large distances. Our results contribute to an improved description of the Interaction between colloidal particles trapped at fluid interfaces.

  • Electrostatic Interaction between colloidal particles trapped at an electrolyte interface
    arXiv: Soft Condensed Matter, 2014
    Co-Authors: Arghya Majee, Markus Bier, S Dietrich
    Abstract:

    The Electrostatic Interaction between colloidal particles trapped at the interface between two immiscible electrolyte solutions is studied in the limit of small inter-particle distances. Within an appropriate model exact analytic expressions for the Electrostatic potential as well as for the surface and line Interaction energies are obtained. They demonstrate that the widely used superposition approximation, which is commonly applied to large distances between the colloidal particles, fails qualitatively at small distances and is quantitatively unreliable even at large distances. Our results contribute to an improved description of the Interaction between colloidal particles trapped at fluid interfaces.

Philip Coppens - One of the best experts on this subject based on the ideXlab platform.

  • dependence of the intermolecular Electrostatic Interaction energy on the level of theory and the basis set
    Journal of Chemical Theory and Computation, 2006
    Co-Authors: Anatoliy Volkov, Harry F King, Philip Coppens
    Abstract:

    As Electrostatic forces play a prominent role in the process of folding and binding of biological macromolecules, an examination of the method dependence of the Electrostatic Interaction energy is of great importance. An extensive analysis of the basis set and method dependence of Electrostatic Interaction energies (Ees) in molecular systems using six test dimers of α-glycine is presented. A number of Hartree−Fock, Kohn−Sham, Moller−Plesset, configuration Interaction (CI), quadratic CI, and coupled cluster calculations were performed using several double-, triple-, and quadruple-ζ-quality Gaussian- and Slater-type (Kohn−Sham calculations only) basis sets. The main factor affecting Ees was found to be the inclusion of diffuse functions in the basis set expansions. Moller−Plesset (even at second order), quadratic CI, and coupled cluster calculations produce the most consistent results. Hartree−Fock and CI methods usually overestimate the Ees, while the Kohn−Sham approach tends to underestimate the magnitude...

  • combination of the exact potential and multipole methods ep mm for evaluation of intermolecular Electrostatic Interaction energies with pseudoatom representation of molecular electron densities
    Chemical Physics Letters, 2004
    Co-Authors: Anatoliy Volkov, T Koritsanszky, Philip Coppens
    Abstract:

    Abstract A new method (EP/MM) for calculation of intermolecular Electrostatic Interaction energies from pseudoatom expansions of molecular densities is presented. It combines numerical evaluation of the exact Coulomb integral for the short-range with the Buckingham-type multipole approximation for the long-range interatomic Interactions. In first instance the method is combined with the pseudoatom representation of the atomic densities as derived from theoretical wavefunctions. The resulting Electrostatic Interaction energies of monomers in molecular dimers are in very good agreement with Morokuma–Ziegler decompositioning of triple-zeta DFT energies. The combination of EP/MM with densities from the theoretical databank of aspherical pseudoatoms provides more accurate results than the MMFF94 force-field at a moderate increase in computing time. EP/MM is also applicable to experimental electron densities.