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Item type:Publication, Access status: with files , Efficient treatment of long-range electrostatics in charge equilibration approaches(American Institute of Physics (AIP), 2025-05-07); ; ; ; A charge equilibration method based on real-space Gaussians as charge densities is presented. The implementation is part of the Electrode package available in the Large-scale Atomic/Molecular Massively Parallel Simulator and benefits from its efficient particle-mesh Ewald approach. A simple strategy required to switch from the previously used Slater-type orbital (STO) shielding to Gaussians is provided by fitting the Coulomb energy of two Gaussian charge distributions to the repulsion between two STOs. Their widths were optimized for O, Si, and Ti species, obtaining results consistent with previous studies using STOs in the case of SiO2 polymorphs. In the limit of sufficiently narrow Gaussians, it is shown that the implementation converges to electronegativity equalization method results for the case of Ti/TiOx interfaces. The method presented is implemented in a way that is potentially beneficial for the application of modern machine-learning force fields that include long-range electrostatic interactions.Publicationtype: Journal Article36 75 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Strong macroscale supercrystalline structures by 3D printing combined with self-assembly of ceramic functionalized nanoparticles(Wiley-VCH, 2020-04-29); ; ; ; To translate the exceptional properties of colloidal nanoparticles (NPs) to macroscale geometries, assembly techniques must bridge a 106-fold range of length. Moreover, for successfully attaining a final mechanically robust nanocomposite macroscale material, some of the intrinsic NPs’ properties have to be maintained while minimizing the density of strength-limiting defects. However, the assembly of nanoscale building blocks into macroscopic dimensions, and their effective macroscale properties, are inherently affected by the precision of the conditions required for assembly and emergent flaws including point defects, dislocations, grain boundaries, and cracks. Herein, a direct-write self-assembly technique is used to construct free-standing, millimeter-scale columns comprising spherical iron oxide NPs (15 nm diameter) surface functionalized with oleic acid (OA), which self-assemble into face-centered cubic (FCC) supercrystals in minutes during the direct-writing process. The subsequent crosslinking of OA molecules results in nanocomposites with a maximum strength of 110 MPa and elastic modulus up to 58 GPa. These mechanical properties are interpreted according to the flaw size distribution and are as high as newly engineered platelet-based nanocomposites. The findings indicate a broad potential to create mechanically robust, multifunctional 3D structures by combining additive manufacturing with colloidal assembly.Publicationtype: Journal ArticleScopus© Citations 17 304 287 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Impact of the Conformational Variability of Oligopeptides on the Computational Prediction of Their CD Spectra(2019-08-08); ; ; ; Although successful in the structural determination of ordered biomolecules, the spectroscopic investigation of oligopeptides in solution is hindered by their complex and rapidly changing conformational ensemble. The measured circular dichroism (CD) spectrum of an oligopeptide is an ensemble average over all microstates, severely limiting its interpretation, in contrast to ordered biomolecules. Spectral deconvolution methods to estimate the secondary structure contributions in the ensemble are still mostly based on databases of larger ordered proteins. Here, we establish how the interpretation of CD spectra of oligopeptides can be enhanced by the ability to compute the same observable from a set of atomic coordinates. Focusing on two representative oligopeptides featuring a known propensity toward an α-helical and β-hairpin motif, respectively, we compare and cross-validate the structural information coming from deconvolution of the experimental CD spectra, sequence-based de novo structure prediction, and molecular dynamics simulations based on enhanced sampling methods. We find that small conformational variations can give rise to significant changes in the CD signals. While for the simpler conformational landscape of the α-helical peptide de novo structure prediction can already give reasonable agreement with the experiment, an extended ensemble of conformers needs to be considered for the β-hairpin sequence.Publicationtype: Journal Article112