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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Direct Deoxygenation of Phenol over Fe-Based Bimetallic Surfaces Using On-the-Fly Surrogate Models

We present an accelerated nudged elastic band (NEB) study of phenol direct deoxygenation (DDO) on Fe-based bimetallic surfaces using a recently developed Gaussian process regression (GPR) calculator. Our test calculations demonstrate that the GPR calculator achieves up to 3 times speedup compared to conventional density functional theory calculations while maintaining high accuracy, with energy barrier errors below 0.015 eV. Using GPR-NEB, we systematically examine the DDO mechanism on pure Fe(110) and surfaces modified with Co and Ni in both top and subsurface layers. Our results show that subsurface Co and Ni substitutions preserve favorable thermodynamics and kinetics for both C–O bond cleavage and C–H bond formation, comparable to those on the pure Fe(110) surface. In contrast, top-layer substitutions generally increase the C–O bond cleavage barrier, render the step endothermic, and result in significantly higher reverse reaction rates, making DDO unfavorable on these surfaces. This work demonstrates the effectiveness of GRR-accelerated transition state searches for complex surface reactions and provides insights into rational design of bimetallic catalysts for selective deoxygenation.

Aromatic compounds↗
DOE OSTI2011

On-the-Fly Identification of Conformational Substates from Molecular Dynamics Simulations

We recently introduced a new method for discovering, characterizing, and monitoring spatiotemporal patterns in the conformational fluctuations in molecular dynamics simulation data ( J. Comput. Biol. 2010, 17 (3), 309 324). Significantly, our method, called Dynamic Tensor Analysis (DTA), can be performed as the simulation is progressing. It is therefore well-suited to analyzing long timescale simulations, which are critical for studying biologically relevant motions but may be too large for traditional analysis methods. In this paper, we demonstrate that the patterns discovered by DTA often correspond to functionally important conformational substates. In particular, we apply DTA to a 150 ns simulation of ubiquitin and discover patterns that provide unique insights into ubiquitin's ability to bind multiple substrates. Moreover, we take advantage of DTA's ability to identify patterns on different timescales and investigate how fast positional fluctuations may modulate slower, large-scale motions in functionally important regions. Our findings here suggest that DTA is well-suited to organizing, visualizing, and analyzing very large trajectories and discovering conformational substates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗