SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Correction for ‘Isolation of C1 through C4 derivatives from CO using heteroleptic uranium( iii ) metallocene aryloxide complexes’ by Robert J. Ward et al. , Chem. Sci. , 2023, 14 , 2024–2032, https://doi.org/10.1039/D2SC06375A.
Correction for ‘Magnetic coupling between Fe(NO) spin probe ligands through diamagnetic Ni II , Pd II and Pt II tetrathiolate bridges’ by Manuel Quiroz et al. , Chem. Sci. , 2023, 14 , 9167–9174, https://doi.org/10.1039/D3SC01546G.
Bi 2 S 3 is a narrow bandgap semiconductor of interest for the construction of solar energy devices and can be synthesized by E-Chem/Sulfurization approach. The (photo)current from Bi 2 S 3 can be controlled by the substrate workfunction and its resistance.
Correction for ‘Single and dual metal atom catalysts for enhanced singlet oxygen generation and oxygen reduction reaction’ by Mohsen Tamtaji et al. , J. Mater. Chem. A , 2023, https://doi.org/10.1039/D2TA08240C.
Correction for ‘Porous bipolar polymers as organic cathodes for sustainable sodium/potassium-ion batteries’ by Motahareh Mohammadiroudbari et al. , J. Mater. Chem. A , 2023, https://doi.org/10.1039/D3TA02445H.
Correction for ‘Accelerating materials discovery using integrated deep machine learning approaches’ by Weiyi Xia et al. , J. Mater. Chem. A , 2023, 11 , 25973–25982, https://doi.org/10.1039/d3ta03771a.
Correction for ‘Thorium amidates function as single-source molecular precursors for thorium dioxide’ by Mark D. Straub et al. , Chem. Commun. , 2021, 57 , 4954–4957, https://doi.org/10.1039/D1CC00867F.
Correction for ‘Improving the direct air capture capacity of grafted amines via thermal treatment’ by Melinda L. Jue et al. , Chem. Commun. , 2024, 60 , 7077–7080, https://doi.org/10.1039/D4CC01634C.
Correction for ‘Impacts of trace level chromium on formation of superoxide within uranyl triperoxide complexes’ by Sarah K. Scherrer et al. , Chem. Commun. , 2024, 60 , 10584–10587, https://doi.org/10.1039/D4CC03194F.
Correction for ‘Characterization of polymer properties and identification of additives in commercially available research plastics’ by Amy A. Cuthbertson et al. , Green Chem. , 2024, https://doi.org/10.1039/d4gc00659c.
Correction for ‘Minimising the payload solvent exposed hydrophobic surface area optimises the antibody–drug conjugate properties’ by Adrian D. Hobson et al. , RSC Med. Chem. , 2024, https://doi.org/10.1039/d3md00540b.
Correction for ‘Ion pair extractant selective for LiCl and LiBr’ by Nam Jung Heo et al. , Chem. Sci. , 2024, 15 , 13958–13965, https://doi.org/10.1039/D4SC03760J.
Correction for ‘Infrared spectroscopy for understanding the structure of Nafion and its associated properties’ by Tanya Agarwal et al. , J. Mater. Chem. A , 2024, https://doi.org/10.1039/D3TA05653H.
Correction for ‘Reductive catalytic fractionation of agricultural residue and energy crop lignin and application of lignin oil in antimicrobials’ by Elvis Osamudiamhen Ebikade et al. , Green Chem. , 2020, 22 , 7435–7447, https://doi.org/10.1039/D0GC02781B.
Correction for ‘A comprehensive approach for elucidating the interplay between 4f n +1 and 4f n 5d 1 configurations in Ln 2+ complexes’ by Maria J. Beltran-Leiva et al. , Chem. Sci ., 2025, 16 , 2024–2033, https://doi.org/10.1039/d4sc05438e.
Semi-empirical quantum-mechanical (QM) methods have become valuable tools for studying complex (bio)molecular systems due to their balance between computational efficiency and accuracy. A key aspect of these methods is their parameterization, which not only governs the reliability of the results but also provides an opportunity to enhance their overall performance. In our previous work [J. Phys. Chem. Lett., 2021, 11, 16], we advanced the third-order semi-empirical density functional tight-binding (DFTB3) method for computing multiple properties of small molecules by developing the machine learning (ML) potential NN rep to bridge the gap between DFTB3 electronic components and those of the hybrid DFT-PBE0 functional. To overcome the limitations of NN rep , we introduce the EquiDTB framework, which leverages physics-inspired equivariant neural networks (NN) to parameterize scalable and transferable many-body Δ TB potentials, replacing the standard pairwise DFTB repulsive potential. This advancement extends the applicability of our ML-corrected DFTB approach to larger molecules and non-covalent systems (including only C, N, O, and H atoms), going beyond the chemical space represented in the training QM datasets. The enhanced performance of EquiDTB over the standard TB methods is demonstrated by the accurate computation of the atomic forces of S66x8 molecular dimers, as well as their interaction energies. Moreover, EquiDTB can be effectively employed to explore the potential energy surfaces of large and flexible drug-like molecules—for example, to determine the minimum energy path between isomers, analyze structural transitions during dynamical simulations, compute vibrational modes, and investigate energetic rankings. The performance for single molecules slightly decreases when the DFTB electronic energy is reduced to first-order but remains superior to standard TB methods. Our work thus demonstrates that an optimal integration of an equivariant NN with QM datasets can advance the DFTB method while maintaining high efficiency, paving the way for reliable (bio)molecular simulations.
In this paper, we explain a recent experimental observation that the time-resolved electron paramagnetic resonance spectra of an organic molecule for optical excitation within a highly absorbing region of the molecule has similar intensities to the spectra for optical excitation in a nonabsorbing region [D. L. Meyer et al., J. Phys. Chem. Lett. 8, 1677 (2017)]. We demonstrate that this phenomenon is due to an initial-state preparation effect of photoexcitation that leads to similar initial populations of triplet states for both optical excitation regions. Due to the low intersystem crossing rates, the initial triplet populations are not perturbed on the time scale of the experiment, so they determine the relative intensities of the paramagnetic resonance spectra. The effect is surprising given the weak spin-orbit interactions of organic molecules. Such initial-state preparation effects are likely to occur in systems where the intersystem crossing time scales are long compared to the time scale of the experiment.
Convergence with respect to imaginary-time discretization (i.e., the number of ring-polymer beads) is an essential part of any path-integral-based molecular dynamics (MD) calculation. However, an unfortunate property of existing non-preconditioned numerical integration schemes for path-integral molecular dynamics—including essentially all existing ring-polymer molecular dynamics (RPMD) and thermostatted RPMD (T-RPMD) methods—is that for a given MD time step, the overlap between the exact ring-polymer Boltzmann–Gibbs distribution and that sampled using MD becomes zero in the infinite-bead limit. This has clear implications for hybrid Metropolis Monte Carlo/MD sampling schemes, and it also causes the divergence with bead number of the primitive path-integral kinetic-energy expectation value when using standard RPMD or T-RPMD. We show that these and other problems can be avoided through the introduction of “dimension-free” numerical integration schemes for which the sampled ring-polymer position distribution has non-zero overlap with the exact distribution in the infinite-bead limit for the case of a harmonic potential. Most notably, we introduce the BCOCB integration scheme, which achieves dimension freedom via a particular symmetric splitting of the integration time step and a novel implementation of the Cayley modification [R. Korol et al., J. Chem. Phys. 151, 124103 (2019)] for the free ring-polymer half-steps. More generally, we show that dimension freedom can be achieved via mollification of the forces from the external physical potential. The dimension-free path-integral numerical integration schemes introduced here yield finite error bounds for a given MD time step, even as the number of beads is taken to infinity; these conclusions are proven for the case of a harmonic potential and borne out numerically for anharmonic systems that include liquid water. The numerical results for BCOCB are particularly striking, allowing for nearly three-fold increases in the stable time step for liquid water with respect to the Bussi–Parrinello (OBABO) and Leimkuhler (BAOAB) integrators, while introducing negligible errors in the calculated statistical properties and absorption spectrum. Importantly, the dimension-free, non-preconditioned integration schemes introduced here preserve ergodicity and global second-order accuracy, and they remain simple, black-box methods that avoid additional computational costs, tunable parameters, or system-specific implementations.