Inverse Temperature Dependence Research Articles

First-principles study on thermal and electrical transport properties of NbGe2 and NbSi2: the role of electron-phonon coupling

Abstract We study coupled electron and phonon transport in NbX2 with X=Ge, Si, in which experimental evidence of strong electron-phonon coupling and hydrodynamic transport has been reported. Based on first-principles calculations at the density functional theory level, we report their thermal and electrical transport properties. We find that phonon-electron scattering strongly affects their phonon thermal conductivity (κ ph) and leads to weak temperature dependence of κ ph, instead of normal inverse temperature dependence when anharmonic three phonon scattering dominates. Moreover, κ ph contributes to quarter of the total thermal conductivity, which differs from typical metals where total thermal conductivity is predominantly from electron part. Different from previous numerical study, our results of electrical resistivity agree well with experimental measurement. The anisotropic property of the transport coeffcients is attributed to the electron and phonon dispersion relation. Moreover, we find negligible effect of electron-phonon drag on the transport property, contrary to expectation from a strongly coupled electron-phonon fluid.

Thermal conductivity of Al/AlN interpenetrating phase composites with different preform porosity

In this investigation, the thermal conductive (TC) properties of the Al/AlN interpenetrating phase composites (IPCs) with varying preform porosity at different temperatures (20°C to 200°C) were studied. The TC values obtained through experimentation were compared to predictions generated by analytical models. IPCs with higher preform porosity exhibit higher TC. The TC of IPCs exhibits an inverse temperature dependence. Theoretical models accurately predict the thermal conductivity of IPCs with high preform porosity.

Tunable emission color from lead-free zero-dimensional Mn2+-doped Cs3InCl6 single crystals

In recent years, the magneto-optical properties of zero-dimensional metal halides have attracted widespread interest. In this study, we employed a vacuum solid-state reaction method to synthesize zero-dimensional, lead-free, and all-inorganic Cs3InCl6 single crystals (SCs). In addition to the blue emission of self-trapped excitons (STEs) inherent to pristine Cs3InCl6, the strategic doping with Mn2+ ions not only facilitates multicolor emissions but also significantly boosts the photoluminescence quantum yield (PLQY) from a modest 1.21 % to an impressive 32.18 %. We carried out an exhaustive investigation into the fundamental mechanisms responsible for these multicolor emissions and the intricate compositional transitions that ensue. Furthermore, the pronounced correlation between temperature-dependent photoluminescence (PL) and magnetic characteristics unveiled the genesis of ferromagnetism within both the pristine and Cs3InCl6: xMn2+ samples. The doping-induced modifications in magnetic behavior furnish a coherent explanation for the anomalous inverse temperature dependence emission wavelength shift. Our research highlights the adjustable PL and magnetic attributes of Mn2+ doped Cs3InCl6, yielding invaluable insights that are poised to advance its application in the next wave of optoelectronic and magnetic technologies.

Examining the effects of sintering temperature on double perovskite La2NiTiO6: Analysis of structural, optical, electrical properties, and leakage current characteristics

This study explores the influence of varying sintering temperatures on the structural, optical, electrical, and leakage current features of La2NiTiO6 (LNTO), a double perovskite material synthesized through the citrate auto-ignition method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX) analysis were employed to investigate the structure, microstructure, and compositional distribution of the samples. The samples sintered at various temperatures showed the monoclinic structure with space group P21/n and were confirmed by Rietveld's refinement of the XRD patterns. The average grain size increased with higher sintering temperatures, which is consistent with the particle size estimated from the histogram plot of the FE-SEM data. The UV–visible (UV–Vis) spectroscopy showed that the energy band gap decreased as sintering temperatures increased. Impedance spectroscopy analysis revealed non-Debye type relaxation of charge carriers and confirmed the negative temperature coefficient of resistance (NTCR) behavior. Electrical analysis affirmed that the direct current (DC) conductivity is thermally activated, following the Arrhenius equation with an inverse temperature dependency. As the sintering temperature increases, the leakage current density decreases, and the leakage current conforms to the ohmic conduction mechanism.

Solid-State Molecular Protonics Devices of Solid-Supported Biological Membranes Reveal the Mechanism of Long-Range Lateral Proton Transport.

Lateral proton transport (PT) on the surface of biological membranes is a fundamental biochemical process in the bioenergetics of living cells, but a lack of available experimental techniques has resulted in a limited understanding of its mechanism. Here, we present a molecular protonics experimental approach to investigate lateral PT across membranes by measuring long-range (70 μm) lateral proton conduction via a few layers of lipid bilayers in a solid-state-like environment, i.e., without having bulk water surrounding the membrane. This configuration enables us to focus on lateral proton conduction across the surface of the membrane while decoupling it from bulk water. Hence, by controlling the relative humidity of the environment, we can directly explore the role of water in the lateral PT process. We show that proton conduction is dependent on the number of water molecules and their structure and on membrane composition, where we explore the role of the headgroup, the tail saturation, the membrane phase, and membrane fluidity. The measured PT as a function of temperature shows an inverse temperature dependency, which we explain by the desorption and adsorption of water molecules into the solid membrane platform. We explain our findings by discussing the role of percolating hydrogen bonding within the membrane structure in a Grotthuss-like mechanism.

Luminous characteristics of high-voltage blue mini-light-emitting diodes

The luminous characteristics of flip-chip type high-voltage (HV) blue mini-light-emitting diodes (LEDs), which consist of three serially connected sub-mesas, have been investigated for the first time. The cryogenic electroluminescence below 100 K partially originates from localized excitons. As the driving current reaches 1 μA, the contributions of Shockley–Read–Hall nonradiative recombination and radiative recombination exhibit a remarkably inverse temperature dependence, while the contributions of Auger recombination and carrier leakage are relatively negligible. The mesa corresponding to the anode of the HV blue mini-LED exhibits the lowest temperature among the three sub-mesas due to its smaller thermal resistance. To minimize the temperature-induced shift in chromaticity coordinates, it is necessary to adjust the driving current based on the operating temperature.

A neutral germanium-centred hard and soft lewis superacid and its unique reactivity towards hydrosilanes.

The germanium-centred Lewis superacid Ge(pinF)2 (1) was isolated as acetonitrile mono-adduct 1·MeCN and thoroughly characterized by NMR spectroscopy, X-ray crystallography and quantum chemical calculations. Ion abstraction and NMR experiments revealed the hard as well as soft Lewis superacidic nature of 1·MeCN. The title compound readily activates hydrosilanes such as Et3SiH, which is not feasible for its harder silicon homologue 2·MeCN, and even reacts with Et3SiF. The strongly coordinating acetonitrile could be abstracted by B(C6F5), giving the donor-free Ge(pinF)2 (1) and Si(pinF)2 (2) which are Lewis superacids. Unlike 1·MeCN, the donor-free 1 efficiently catalyses hydrosilylation of α-methylstyrene by Et3SiH. For this process, an inverse temperature dependence was observed, i.e. a complete conversion was achieved rapidly when the reaction was cooled to -35 °C, but the reaction stopped at elevated temperatures. Mechanistic investigations, including stoichiometric experiments and quantum chemical calculations, outlined the formation of germylene Ge(pinF) (3), which acts as the active catalyst. The germylene is formed by reductive elimination of the silylated pinacol from the hydrogermane intermediate, which is obtained by the initial reaction of 1 with Et3SiH. The inverse temperature dependence of the catalytic reaction could be explained by low entropy associated with the complexation of two cooperating germylenes and the substrates. With this example we introduce an in situ generated Lewis acidic germylene complex for catalytic hydrosilylation of olefins and again exemplify the great potential of main-group-element-based complexes in catalysis.

Temperature inversion enables superior stability for low-temperature Zn-ion batteries

It is challenging for aqueous Zn-ion batteries (ZIBs) to achieve comparable low-temperature (low-T) performance due to the easy-frozen electrolyte and severe Zn dendrites. Herein, an aqueous electrolyte with a low freezing point and high ionic conductivity is proposed. Combined with molecular dynamics simulation and multi-scale interface analysis (time of flight secondary ion mass spectrometry three-dimensional mapping and in-situ electrochemical impedance spectroscopy method), the temperature independence of the V2O5 cathode and Zn anode is observed to be opposite. Surprisingly, dominated by the solvent structure of the designed electrolyte at low temperatures, vanadium dissolution/shuttle is significantly inhibited, and the zinc dendrites caused by this electrochemical crosstalk are greatly relieved, thus showing an abnormal temperature inversion effect. Through the disclosure and improvement of the above phenomena, the designed Zn||V2O5 full cell delivers superior low-T performance, maintaining almost 99% capacity retention after 9500 cycles (working more than 2500 h) at −20 °C. This work proposes a kind of electrolyte suitable for low-T ZIBs and reveals the inverse temperature dependence of the Zn anode, which might offer a novel perspective for the investigation of low-T aqueous battery systems.

Acetonyl Peroxy and Hydroperoxy Self- and Cross-Reactions: Temperature-Dependent Kinetic Parameters, Branching Fractions, and Chaperone Effects.

The temperature-dependent kinetic parameters, branching fractions, and chaperone effects of the self- and cross-reactions between acetonyl peroxy (CH3C(O)CH2O2) and hydro peroxy (HO2) have been studied using pulsed laser photolysis coupled with infrared (IR) wavelength-modulation spectroscopy and ultraviolet absorption (UVA) spectroscopy. Two IR lasers simultaneously monitored HO2 and hydroxyl (OH), while UVA measurements monitored CH3C(O)CH2O2. For the CH3C(O)CH2O2 self-reaction (T = 270-330 K), the rate parameters were determined to be A = (1.5-0.3+0.4) × 10-13 and Ea/R = -996 ± 334 K and the branching fraction to the alkoxy channel, k2b/k2, showed an inverse temperature dependence following the expression, k2b/k2 = (2.27 ± 0.62) - [(6.35 ± 2.06) × 10-3] T(K). For the reaction between CH3C(O)CH2O2 and HO2 (T = 270-330 K), the rate parameters were determined to be A = (3.4-1.5+2.5) × 10-13 and Ea/R = -547 ± 415 K for the hydroperoxide product channel and A = (6.23-4.4+15.3) × 10-17 and Ea/R = -3100 ± 870 K for the OH product channel. The branching fraction for the OH channel, k1b /k1, follows the temperature-dependent expression, k1b/k1 = (3.27 ± 0.51) - [(9.6 ± 1.7) × 10-3] T(K). Determination of these parameters required an extensive reaction kinetics model which included a re-evaluation of the temperature dependence of the HO2 self-reaction chaperone enhancement parameters due to the methanol-hydroperoxy complex. The second-law thermodynamic parameters for KP,M for the formation of the complex were found to be ΔrH250K° = -38.6 ± 3.3 kJ mol-1 and ΔrS250K° = -110.5 ± 13.2 J mol-1 K-1, with the third-law analysis yielding ΔrH250K° = -37.5 ± 0.25 kJ mol-1. The HO2 self-reaction rate coefficient was determined to be k4 = (3.34-0.80+1.04) × 10-13 exp [(507 ± 76)/T]cm3 molecule-1 s-1 with the enhancement term k4,M″ = (2.7-1.7+4.7) × 10-36 exp [(4700 ± 255)/T]cm6 molecule-2 s-1, proportional to [CH3OH], over T = 220-280 K. The equivalent chaperone enhancement parameter for the acetone-hydroperoxy complex was also required and determined to be k4,A″ = (5.0 × 10-38 - 1.4 × 10-41) exp[(7396 ± 1172)/T] cm6 molecule-2 s-1, proportional to [CH3C(O)CH3], over T = 270-296 K. From these parameters, the rate coefficients for the reactions between HO2 and the respective complexes over the given temperature ranges can be estimated: for HO2·CH3OH, k12 = [(1.72 ± 0.050) × 10-11] exp [(314 ± 7.2)/T] cm3 molecule-1 s-1 and for HO2·CH3C(O)CH3, k15 = [(7.9 ± 0.72) × 10-17] exp [(3881 ± 25)/T] cm3 molecule-1 s-1. Lastly, an estimate of the rate coefficient for the HO2·CH3OH self-reaction was also determined to be k13 = (1.3 ± 0.45) × 10-10 cm3 molecule-1 s-1.

Effect of Strand Damage in Nb3Sn Rutherford Cables on the Quench Propagation in Accelerator Magnets

Accelerator magnets employing Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Rutherford cables are more susceptible to conductor degradation than Nb-Ti magnets. Recent measurements on a Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn accelerator magnet have revealed unexpected behaviour such as decaying voltages at constant current plateaus of V-I measurements, inverse ramp rate and temperature dependence of quench currents, and anomalous quench propagation measured by so-called quench antennas. Numerical modelling has shown that these anomalies can be explained by an inhomogeneous degradation in the Rutherford cable, in which a subset of strands is fully or partially degraded. In this paper, we study how this type of degradation can affect the early stages of quench propagation. With the aid of a network model, we show how quench antenna signals can be used to diagnose inhomogeneous conductor degradation in the Rutherford cable.

Characterization of sulfasalazine-bovine serum albumin and human serum albumin interaction by spectroscopic and theoretical approach

The interaction of sulfasalazine (SZ) with the carrier proteins bovine serum albumin (BSA) and human serum albumin (HSA) was explored by fluorescence, absorption and circular dichroism (CD) spectroscopy along within silicotechniques. The spectral alteration observed in fluorescence, absorption and CD spectra upon the addition of SZ confirmed the complex formation of SZ with BSA and HSA. The inverse temperature dependence behaviour of theKsvvalues as well as the increase in the protein’s absorption signals after the addition of SZ indicate that SZ triggered quenching of BSA/HSA fluorescence as the static quenching. The binding affinity (kb) of the order of 106 M−1 was reported towards the BSA-SZ and HSA-SZ association process. Interpretation of thermodynamic data (enthalpy change = -93.85 kJ mol−1and entropy change = -200.81 J mol−1K−1for BSA-SZ system; enthalpy change = -74.12 kJ mol−1and entropy change = -123.90 J mol−1K−1for HSA-SZ system) anticipated that hydrogen bond and van der Waals forces were the main intermolecular forces in the complex stabilization. Inclusion of SZ to BSA/HSA produced microenvironmental perturbations around Tyr and Trp residues. The UV, synchronous and 3D analysis confirmed the structural alteration of proteins after SZ binding, which was supported by CD results. The binding location of SZ in BSA/HSA was detected in Sudlow’s site I (subdomain IIA) and the same was revealed by competitive site-marker displacement investigations. Density functional theory study was done to comprehend the feasibility of the analysis and to optimize the structure and energy gap that validated the experimental results. This study is expected to provide deep information about the pharmacology of SZ with its pharmacokinetic properties.

Unusual Temperature Dependence of Water Sorption in Semicrystalline Hydrogels.

Water vapor sorption is a ubiquitous phenomenon in nature and plays an important role in various applications, including humidity regulation, energy storage, thermal management, and water harvesting. In particular, capturing moisture at elevated temperatures is highly desirable to prevent dehydration and to enlarge the tunability of water uptake. However, owing to the thermodynamic limit of conventional materials, sorbents inevitably tend to capture less water vapor at higher temperatures, impeding their broad applications. Here, an inverse temperature dependence of water sorption in poly(ethylene glycol) (PEG) hydrogels, where their water uptake can be doubled with increasing temperature from 25 to 50°C, is reported. With mechanistic modeling of water-polymer interactions, this unusual water sorption is attributed to the first-order phase transformation of PEG structures, and the key parameters for a more generalized strategy in materials development are identified. This work elucidates a new regime of water sorption with an unusual temperature dependence, enabling a promising engineering space for harnessing moisture and heat.

A REE-based zircon geothermometer based on improved lattice strain modeling of zircon-melt REE partition coefficients

Several methods for tracing geological processes based on the rare earth element (REE) concentrations in zircon have been proposed in recent years. Application of these methods requires quantitative knowledge of the partition coefficients (D) for the REE between zircon and co-existing phases, which may be melt, fluid, or other minerals. Precisely determining the DREE of zircon, however, is challenging. This is especially true for the light rare earth elements, which generally occur in very low concentrations in zircon. This difficulty can be overcome by modeling DREE using a prediction function based on the crystal lattice strain model. The prediction function is defined by three empirically derived lattice strain parameters: the apparent Young's Modulus E of the Zr site in which the REE resides; the ionic radius r0 of a (fictive) REE optimally fitting into this site; and the maximum partition coefficient D0 of this optimally fitting REE. In principle, these three parameters can be determined by fitting the prediction function to sets of measured DREE. The ionic radii of the REE, however, are all larger than r0 for zircon, commonly resulting in strain model fits yielding physically unrealistic values of r0, in particular. Here, we use a compilation of zircon-melt REE partition coefficients from the literature to establish a new empirical relationship between r0 and E, which is used as an additional constraint during lattice strain model curve fitting. Lattice strain parameters for literature DREE data sets of natural and synthetic zircon samples are calculated using our constraint resulting in a new parametrization of the inverse temperature dependence of D0. This parametrization enables quantitative estimates of REE-based crystallization temperatures of magmatic zircons, complementing estimates based on Ti-in-zircon geothermometry.

Características termoreologicas e aptidão de extrudabilidade de um novo amido de mandioca sem amilose

ABSTRACT Cassava crops have always been fundamental in human nutrition and industry. Nowadays, the development of new cultivars with specific properties has become a major research area. In this research, amylose-free cassava starch (WXCS) extracted from clone AM206-5 was evaluated with respect to its physicochemical, morphological, and thermorheological properties. The waxy nature of cassava starch was verified (0.54 ± 0.09% w/w amylose), showing a 16.92±0.20 µm average granule size and elliptical or spherical truncated shapes without granule aggregation. There were significant differences in the pasting profiles evaluated, with WXCS being thermally less stable (Breakdown = 698±2 cP) generating less viscous final pastes (731±16 cP) compared to a commercial amylose-free corn starch. The WXCS shear viscosity was determined in a capillary rheometer (Rheoplast®), showing an inverse linear temperature dependence, decreasing by a factor larger than 3 when the temperature changed from 100 to 120 °C, with a pseudoplastic flow described by the power law (n: 0.25-0.40), consistency index (32607 - 6695 Pa.s) and specific mechanical energy (124 - 75 J/g). The extensional viscosity was always higher than the shear viscosity, where increasing the strain rate and temperature enlarged the Trouton number (25-145). Complete WXCS transformation under real process conditions was achieved with a 30% w/w moisture content and 100 °C, which induced full granular integrity loss and crystalline structure destruction. The results confirmed a potential utilization for this new starch to obtain extruded-type food products or to serve as a biothickening agent.

Sublinear temperature dependence of thermal conductivity in the incommensurate phase of TlInTe2

Thermal conductivity $(\ensuremath{\kappa})$ of semiconducting and insulating solids generally show inverse linear temperature dependence above the Debye temperature $({T}_{\mathrm{D}})$ owing to dominant phonon-phonon scattering, i.e, $\ensuremath{\kappa}\ensuremath{\propto}{T}^{\ensuremath{-}1}$. Recently, in ultralow $\ensuremath{\kappa}$ materials, $\ensuremath{\kappa}$ is found to decrease sublinearly ($\ensuremath{\kappa}\ensuremath{\propto}{T}^{\ensuremath{-}\ensuremath{\alpha}}$ where $0&lt;\ensuremath{\alpha}&lt;1$) above ${T}_{\mathrm{D}}$ as interbranch wavelike tunneling contribution becomes significant. Here we show that the deviation from linearity can be unprecedently large in incommensurate (IC) phases as exemplified by archetypal Zintl-like semiconductor ${\mathrm{TlInTe}}_{2}$. This happens because two mutually incompatible translational symmetries allow spatially and temporally varying phase shifts, thus giving rise to two new heat-carrying modes: phasons and amplitudons. Using comprehensive transport and spectroscopy measurements combined with first-principles simulations of multichannel thermal transport, i.e., phonon-phonon scattering and tunneling contributions, we find that new modes contribute nearly 10-30% of the total $\ensuremath{\kappa}$ near the IC transition. The origin of this IC transition is rooted in the Tl lone pair and large polarizability of the electronic cloud, whose fingerprints are visible in the phonon linewidths. Our study paves the way for understanding ultralow $\ensuremath{\kappa}$ in IC phases, particularly for charge-density-wave materials where IC modulation is ubiquitous.

Characterization of Climbazole–Bovine serum albumin interaction by experimental and in silico approaches

Interactive association of an antifungal drug, climbazole (CBZ) with the carrier protein in bovine circulation, bovine serum albumin (BSA) was explored by fluorescence and absorption spectroscopy along with in silico techniques. The fluorescence and absorption spectral alterations of the protein upon addition of CBZ affirmed the complex foration between CBZ and BSA. The inverse temperature dependence behaviour of the KSV values as well as the hyperchromic result of the protein’s absorption signals characterized CBZ-triggered quenching of BSA fluorescence as the static quenching. A weak binding affinity (Ka = 3.12–1.90-× 103 M−1) was reported towards the CBZ−BSA association process. Interpretation of thermodynamic data (entropy change = +14.68 J mol−1 K−1 and enthalpy change = –15.07 kJ mol−1) and in silico analyses anticipated that hydrophobic forces, van der Waals forces and hydrogen bonds were the key intermolecular forces in the complex stabilization. Inclusion of CBZ to BSA produced microenvironmental perturbations around Tyr and Trp residues, and also significantly defended temperature-induced destabilization of BSA. The binding locus of CBZ was detected in the proximity of Sudlow’s sites I (subdomain IIA) and II (subdomain IIIA) of BSA, exhibiting greater preference towards site II, as revealed by competitive site-marker displacement investigations and in silico analysis. The stability of the CBZ–BSA complex was further validated by the molecular dynamics simulation assessments.

Quantum criticality at finite temperature for two-dimensional [formula omitted] models on the square and the honeycomb lattices

We study the quantum criticality at finite temperature for three two-dimensional (2D) JQ3 models using the first principles quantum Monte Carlo calculations (QMC). In particular, the associated universal quantities are obtained, and their inverse temperature dependence is investigated. The considered models are known to have quantum phase transitions from the Néel order to the valence-bond solid, and these transitions are shown to be possibly of second order for two of the studied models, with the remaining one being of first order. When the temperature dependence of the studied universal quantities is considered, we observe substantial differences between the two models likely possessing second-order phase transitions and the remaining model. Moreover, by using the associated data from both the models that may have continuous transitions, good data collapses are obtained for a number of the considered universal quantities. The findings presented here provide numerical evidence to support particular results established in the literature regarding the nature of the phase transitions of these JQ3 models, and can be employed as useful criterions to distinguish second-order phase transitions from first-order ones for the exotic criticalities of the JQ-type models.

Charpy impact behavior and deformation mechanisms of Cr26Mn20Fe20Co20Ni14 high-entropy alloy at ambient and cryogenic temperatures

Stacking fault energy (SFE) of high- and medium-entropy alloys (HEAs and MEAs) can be tuned by tailoring the constituent. In this work, we prepared a non-equiatomic Cr26Mn20Fe20Co20Ni14 HEA with low SFE and investigated the Charpy impact behavior at 298 and 77 K, respectively. The Cr26Mn20Fe20Co20Ni14 HEA performs an inverse temperature dependence of absorbed impact energy, in contrast to the slight decrease of the equiatomic CrMnFeCoNi HEA. Detailed microstructural investigation along the cracks reveals that dislocation pilling-up and nano-twinning are the dominant strengthening mechanisms for the Cr26Mn20Fe20Co20Ni14 HEA at 298 K and the CrMnFeCoNi HEA at 298 and 77 K. For Cr26Mn20Fe20Co20Ni14 HEA at 77 K, except for the enhanced twinning and dislocation storage, additional hexagonal close packed (HCP) structured ε phase transformation also occurred, contributing to the higher strain hardening ability and impact toughness. This study provides experimental evidence for designing HEAs for potential cryogenic applications.

Validating experiments for the reaction H2 + NH2- by dynamical calculations on an accurate full-dimensional potential energy surface.

Ion-molecule reactions play key roles in the field of ion related chemistry. As a prototypical multi-channel ion-molecule reaction, the reaction H2 + NH2- → NH3 + H- has been studied for decades. In this work, we develop a new globally accurate potential energy surface (PES) for the title system based on hundreds of thousands of sampled points over a wide dynamically relevant region that covers long-range interacting configuration space. The permutational invariant polynomial-neural network (PIP-NN) method is used for fitting and the resulting total root mean squared error (RMSE) is extremely small, 0.026 kcal mol-1. Extensive dynamical and kinetic calculations are carried out on this PIP-NN PES. Impressively, a unique phenomenon of significant reactivity suppression by exciting the rotational mode of H2 is reported, supported by both the quasi-classical trajectory (QCT) and quantum dynamics (QD) calculations. Further analysis uncovers that exciting the H2 rotational mode would prevent the formation of the reactant complex and thus suppress the reactivity. The calculated rate coefficients for H2/D2 + NH2- agree well with the experimental results, which show an inverse temperature dependence from 50 to 300 K, consistent with the capture nature of this barrierless reaction. The significant kinetic isotope effect observed by experiments is well reproduced by the QCT computations as well.

Master-equation-based approach to stochastic processes in few-electron systems and advanced considerations for practical applications

This paper revisits the master-equation-based approach to physical parameters to characterize transport in three-dimensional and low-dimensional few-electron systems. Advanced expressions of the electron density are theoretically derived at equilibrium for a system having traps. It is revealed that electron density at equilibrium is slightly higher than that without any interface traps as a result of the influence of dynamic trapping/detrapping processes. The capture time constant of electrons applicable to practical systems having traps, such as silicon-related materials, is also theoretically derived. The theoretical model is examined by numerical calculations and experimental results. In wire-type metal–oxide–semiconductor devices, the capture-time constant model roughly reproduces its inverse-temperature dependence. The effective activation energy of the capture time constant is not significantly influenced by that of the emission time constant. In the conductive filaments of silicon oxide film created by electrical stress, the capture-time constant model basically reproduces its inverse-temperature dependence. The effective activation energy of the capture time constant is not significantly influenced by that of the emission time constant but is influenced by the cross-sectional area of the filament and the electron density in the filament. The capture-time constant model semi-quantitatively reproduces the experimentally observed bias dependence of the silicon oxide film. Numerical calculation results suggest that the carrier transit time assumed in the model depends on the physical properties of the materials used. Given the goal of this study, the theoretical approach basically produces successful results.