arXiv subjects

Juan D. Olarte-Plata

Publications and source records attributed to Juan D. Olarte-Plata.

4 recordsLinked to original sources

arXiv2025

Force-Free Molecular Dynamics Through Autoregressive Equivariant Networks

Molecular dynamics (MD) simulations play a crucial role in scientific research. Yet their computational cost often limits the timescales and system sizes that can be explored. Most data-driven efforts have been focused on reducing the computational cost of accurate interatomic forces required for solving the equations of motion. Despite their success, however, these machine learning interatomic potentials (MLIPs) are still bound to small time-steps. In this work, we introduce TrajCast, a transferable and data-efficient framework based on autoregressive equivariant message passing networks that directly updates atomic positions and velocities lifting the constraints imposed by traditional numerical integration. We benchmark our framework across various systems, including a small molecule, crystalline material, and bulk liquid, demonstrating excellent agreement with reference MD simulations for structural, dynamical, and energetic properties. Depending on the system, TrajCast allows for forecast intervals up to $30\times$ larger than traditional MD time-steps, generating over 15 ns of trajectory data per day for a solid with more than 4,000 atoms. By enabling efficient large-scale simulations over extended timescales, TrajCast can accelerate materials discovery and explore physical phenomena beyond the reach of traditional simulations and experiments. An open-source implementation of TrajCast is accessible under https://github.com/IBM/trajcast.

physics.comp-ph↗

arXiv2024

The impact of the interfacial Kapitza resistance on colloidal thermophoresis

Thermal gradients impart thermophoretic forces on colloidal particles, pushing colloids towards cold or hot regions, a phenomenon called thermophoresis. Current theoretical approaches relate the Soret coefficient to local changes in the interfacial tension around the colloid, which lead to fluid flow around the colloid surface. The Kapitza resistance, a key variable in the description of interfacial heat transport, is an experimentally accessible property that modifies interfacial thermal fields. Here, we introduce a theoretical approach that describes colloid thermophoretic forces by incorporating explicitly Kapitza resistance effects. Our formulation can be used to monitor the dependence of thermophoresis on the interfacial thermal resistance. We show that the resistance modifies the thermal field around the colloids and identify experimental conditions where the Kapitza resistance influences the thermophoretic forces. We validate our theoretical approach by implementing a non-equilibrium molecular dynamics model of a colloid suspended in a solvent.

cond-mat.soft↗

arXiv2022

Enhanced thermo-optical response by means of anapole excitation

High refractive index dielectric nanostructures offer a versatile platform to control light-matter interaction at the nanoscale as they can easily support electric and magnetic modes with low losses. An additional property that makes them extraordinary is that they can support low radiative modes, so-called anapole modes. In this work, we propose a spectrally tunable anapole nanoheater based on the use of a dielectric anapole resonator able to amplify ten-fold the thermal response of a plasmonic nanoheater. This would allow the use of lower light intensities to achieve striking heating effects. As proof of concept, we perform a detailed study of the thermo-plasmonic response of a gold nanoring used as heating source and a silicon disk, designed to support anapole modes, located in its center acting as anapolar resonator. Furthermore, we utilize the anapole excitation to easily shift the thermal response of these structures from SWIR to the NIR range.

physics.optics↗

arXiv2020

The influence of surface roughness on the adhesive interactions and phase behavior of suspensions of calcite nanoparticles

We investigate the impact of nanoparticle roughness on the phase behaviour of suspensions in models of calcium carbonate nanoparticles. We use a Derjaguin approach that incorporates roughness effects and interactions between the nanoparticles modelled with a combination of DLVO forces and hydration forces, derived using experimental data and atomistic molecular dynamics simulations, respectively. Roughness effects, such as atomic steps or terraces appearing in mineral surfaces result in very different effective inter-nanoparticle potentials. Using stochastic Langevin Dynamics computer simulations and the effective interparticle interactions we demonstrate that relatively small changes in the roughness of the particles modify significantly the stability of the suspensions. We propose that the sensitivity of the phase behavior to the roughness is connected to the short length scale of the adhesive attraction arising from the ordering of water layers confined between calcite surfaces. Particles with smooth surfaces feature strong adhesive forces, and form gel fractal structures, while small surface roughness, of the order of atomic steps in mineral faces, stabilize the suspension. We believe that our work helps to rationalize the contrasting experimental results that have been obtained recently using nanoparticles or extended surfaces, which provide support for the existence of adhesive or repulsive interactions, respectively. We further use our model to analyze the synergistic effects of roughness, pH and ion concentration on the phase behavior of suspensions, connecting with recent experiments using calcium carbonate nanoparticles.

cond-mat.soft↗