Nathan Horst
Iowa State University
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Publication
Featured researches published by Nathan Horst.
Journal of Chemical Physics | 2016
Nathan Horst; Alex Travesset
Driven by the hypothesis that a sufficiently continuous short-ranged potential is able to account for shell flexibility and phonon modes and therefore provides a more realistic description of nanoparticle interactions than a hard sphere model, we compute the solid phase diagram of particles of different radii interacting with an inverse power law potential. From a pool of 24 candidate lattices, the free energy is optimized with respect to additional internal parameters and the p-exponent, determining the short-range properties of the potential, is varied between p = 12 and p = 6. The phase diagrams contain the phases found in ongoing self-assembly experiments, including DNA programmable self-assembly and nanoparticles with capping ligands assembled by evaporation from an organic solvent. The resulting phase diagrams can be mapped quantitatively to existing experiments as a function of only two parameters: Nanoparticle radius ratio (γ) and softness asymmetry.
ACS Nano | 2017
Curt Waltmann; Nathan Horst; Alex Travesset
We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We show that the bonding of two nanocrystals is characterized by ligand textures in the form of vortices. These results are generalized to nanocrystals of different types (differing core and ligand sizes) where the structure of the vortices depends on the softness asymmetry. We provide rigorous calculations for the binding free energy, show that these energies are independent of the chemical composition of the cores, and derive analytical formulas for the equilibrium separation. We discuss the implications of our results for the self-assembly of single-component and binary nanoparticle superlattices. Overall, our results show that the structure of the ligands completely determines the bonding of nanocrystals, fully supporting the predictions of the recently proposed Orbifold topological model.
Journal of Chemical Physics | 2018
Curt Waltmann; Nathan Horst; Alex Travesset
We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We analyze large cores (up to 10 nm in diameter) and ligands with unsaturated carbon bonds (oleic acid) and we investigate the accuracy of the computed potential of mean force by comparing different force fields. We also analyze the vortices that determine the bonding, including the case of asymmetric nanocrystals, and discuss effects related to the intrinsic anisotropy of the core. Overall our results are in agreement with the predictions of the recently proposed orbifold topological model.
Journal of the American Chemical Society | 2018
Tommy Waltmann; Curt Waltmann; Nathan Horst; Alex Travesset
Particle & Particle Systems Characterization | 2018
Srikanth Nayak; Nathan Horst; Honghu Zhang; Wenjie Wang; Surya K. Mallapragada; Alex Travesset; David Vaknin
Bulletin of the American Physical Society | 2018
Thomas Waltmann; Curt Waltmann; Nathan Horst; Alex Travesset
Bulletin of the American Physical Society | 2018
Nathan Horst; Alex Travesset
Bulletin of the American Physical Society | 2018
Curt Waltmann; Nathan Horst; Alex Travesset
ACS Nano | 2018
Curt Waltmann; Nathan Horst; Alex Travesset
Bulletin of the American Physical Society | 2017
Curt Waltmann; Nathan Horst; Alex Travesset