Ab initio electronic-structure calculations of surface catalysis often give changes P0.1 eV for activation energies of intermediate steps when the surface structure or composition is varied, yet P50-fold change in activity according to naive interpretation of the Arrhenius formula is usually not seen in corresponding experiments. To quantitatively analyze this sensitivity inconsistency between ...

The dc and ac electrical transport property of Polyvinyl Alcohol-Multiwall Carbon Nanotubes (PVA-MWNT) composites has been investigated within a temperature range 77≤T≤300K and in the frequency range 20Hz to 1MHz. The temperature variation of dc conductivity gives the presence of two different activation energies. The dielectric properties of the samples have been explained in terms of electric...

The recombination of Frenkel pairs resulting from low energy recoils in 3C-SiC has been investigated using first principles and Nudged Elastic Band calculations. Several recombination mechanisms have been obtained, involving direct interstitial migration, atoms exchange, or concerted displacements, with activation energies ranging from 0.65 eV to 1.84 eV. These results are in agreement with exp...

Many efforts have been made to model adsorption and diffusion processes in metalorganic frameworks (MOFs) in the past several years. In most of these studies, the framework has been kept rigid. In this study, we examine the effect of using a flexible framework model on the self-diffusion coefficients and activation energies calculated for several short n-alkanes and benzene in IRMOF-1 from mole...

Density-functional-theory (DFT) calculations within the generalised gradient approximation (GGA) were used to examine the behaviour of point defects in the cubic BVIO3 perovskite-type oxide, ReO3. Energies of reduction and of hydration were calculated, and the results are compared with literature data for ABO3 perovskite oxides. The activation energies of migration were determined for O2-, H+, ...

The charge behavior of organic light emitting diode (OLED) is investigated by steady-state current-voltage technique and impedance spectroscopy at various temperatures to obtain activation energies of charge injection and transport processes. Good agreement of activation energies obtained by steady-state and frequency-domain was used to analyze their contributions to the charge injection and tr...

We present a method to study current paths through quantum cascade lasers (QCLs). The temperature dependence of the current is measured at a fixed voltage. At low temperatures we find activation energies that correspond to the energy difference between the injector ground state and the upper laser level. At higher temperatures additional paths with larger activation energies are found. Applicat...

ion at any point of the reaction coordinate. However, in this approximation, some systems present spurious negative activation energies. Johnston and Parr 3 addressed this problem by introducing an anti-Morse function to describe the triplet repulsion between the end atoms of the three-atom fragment involved in the reactive bonds. A recent evaluation of the BEBO method, involving 97 gas-phase r...

Mechanisms of the deamination reactions of isoguanine with H2O, OH(-), and OH(-)/H2O and of protonated isoguanine (isoGH(+)) with H2O have been investigated by theoretical calculations. Eight pathways, paths A-H, have been explored and the thermodynamic properties (ΔE, ΔH, and ΔG), activation energies, enthalpies, and Gibbs energies of activation were calculated for each reaction investigated. ...

We have examined state filling and thermal activation of carriers in buried InAs self-assembled quantum dots sSAQDsd with excitation-dependent cathodoluminescence sCLd imaging and spectroscopy. The InAs SAQDs were formed during molecular-beam epitaxial growth of InAs on undoped planar GaAs s001d. The intensities of the groundand excited-state transitions were analyzed as a function of temperatu...