SEARCH · Engineering Papers
Results for “Transition states”
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.
Transition-State Analogues of Phenylethanolamine N-Methyltransferase
Abstract not provided
Metal-to-metal communication during the spin state transition of a [2 ? 2] Fe(ii) metallogrid at equ
Explore the source record for details and available documents.
Cobalt as a promising dopant for producing semi-insulating β-Ga 2 O 3 crystals: Charge state transition levels from experiment and theory
Optical absorption and photoconductivity measurements of Co-doped β-Ga 2 O 3 crystals reveal the photon energies of optically excited charge transfer between the Co related deep levels and the conduction or valence band. The corresponding photoionization cross sections are fitted by a phenomenological model considering electron–phonon coupling. The obtained fitting parameters: thermal ionization (zero-phonon transition) energy, Franck–Condon shift, and effective phonon energy are compared with corresponding values predicted by first principle calculations based on density functional theory. A (+/0) donor level ~0.85 eV above the valence band maximum and a (0/-) acceptor level ~2.1 eV below the conduction band minimum are consistently derived. Temperature-dependent electrical resistivity measurement at elevated temperatures (up to 1000 K) yields a thermal activation energy of 2.1 ± 0.1 eV, consistent with the position of the Co acceptor level. Furthermore, the results show that Co doping is promising for producing semi-insulating β-Ga 2 O 3 crystals.
Charge state transition levels of Ni in $β$-Ga 2 O 3 crystals from experiment and theory: An attractive candidate for compensation doping
Nickel-doped β-Ga 2 O 3 crystals were investigated by optical absorption and photoconductivity, revealing Ni-related deep levels. Here, the photoconductivity spectra were fitted using the phenomenological Kopylov and Pikhtin model to identify the energy of the zero-phonon transition (thermal ionization), Franck–Condon shift, and effective phonon energy. The resulting values are compared with the predicted ones by first-principle calculations based on the density functional theory (DFT). An acceptor level (0/-) of 1.9 eV and a donor level (+/0) of 1.1 eV above the valence band minimum are consistently determined for Ni Ga , which preferentially incorporates on the octahedrally coordinated Ga site. Temperature-dependent resistivity measurements yield a thermal activation energy of ~2.0 eV that agrees well with the determined Ni acceptor level. Conclusively, Ni is an eminently suitable candidate for compensation doping for producing semi-insulating β-Ga 2 O 3 substrates due to the position of the acceptor level (below and close to the mid-bandgap).
Entanglement and absorbing-state transitions in interactive quantum dynamics
Not provided.
Mapping state transition susceptibility in quantum annealing
Not Available
Pynta: Using Machine Learning to Improve High Throughput Discovery of Transition States and Calculation of Surface and Gas-Surface Kinetics
Explore the source record for details and available documents.
Transitional States During Compound Extreme Events: Examples from Cascading Wildfires and Floods
Explore the source record for details and available documents.
Transitional states during compound extreme events and power outages
Explore the source record for details and available documents.
Long-term variability of Swift J1753.5−0127: X-ray spectral–temporal correlations during state transitions
Explore the source record for details and available documents.
Insights into the Catalytic Mechanism and Transition State Stabilization of 5′‐Methylthioadenosine Nucleosidase using Neutron Crystallography
Explore the source record for details and available documents.
Vibrational excitation in some four-center transition states.
Substitution rates for homogeneous deuterium- hydrogen exchange reactions controlled by vibrational excitation
The application of the time-dependent Hartree-Fock method to the calculation of excited state-excited state transition densities of atoms /molecules/
Explore the source record for details and available documents.
Field ionization kinetic and electron impact studies of gas phase transition states - The cyclic bromonium ion
Cis- and trans-isomers of 4-t-butylcyclohexyl bromide were studied to determine the mechanism of cyclic bromonium ion formation. The field ionization kinetic and electron impact data indicate that the formation of the cyclic structure occurs simultaneously with loss of the neutral fragment. The data also show that little or no gas-phase cis-trans isomerization occurs.
Use of scaled external correlation, a double many-body expansion, and variational transition state theory to calibrate a potential energy surface for FH2
New ab initio results and a double many-body expansion formalism have been used to parameterize a new FH2 potential energy surface with improved properties near the saddle point and in the region of long-range attraction. The functional form of the new surface includes dispersion forces by a double many-body expansion. Stationary point properties for the new surface are calculated along with the product-valley barrier maxima of vibrationally adiabatic potential curves for F + H2 - HF(nu-prime = 3) + H, F + HD - HF(nu-prime = 3) + D, and F + D2 - DF(nu-prime = 4) + D. The new surface should prove useful for studying the effect on dynamics of a low, early barrier with a wide, flat bend potential.
Improved techniques for outgoing wave variational principle calculations of converged state-to-state transition probabilities for chemical reactions
Improved techniques and well-optimized basis sets are presented for application of the outgoing wave variational principle to calculate converged quantum mechanical reaction probabilities. They are illustrated with calculations for the reactions D + H2 yields HD + H with total angular momentum J = 3 and F + H2 yields HF + H with J = 0 and 3. The optimization involves the choice of distortion potential, the grid for calculating half-integrated Green's functions, the placement, width, and number of primitive distributed Gaussians, and the computationally most efficient partition between dynamically adapted and primitive basis functions. Benchmark calculations with 224-1064 channels are presented.