Electronic and elastic properties of metastable ZrN: a joint experimental and theoretical study.

The electronic structures and elastic properties of metastable ZrN phases have been investigated using the first-principles calculations with the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, in comparison with those of the stable ZrN phase. All three metastable ZrN phases (including orthorhombic, spinel and ThP-type phases) are found to be semiconducting with bandgaps of 1.72-1.

The highly exothermic hydrogen abstraction reaction HTe + OH → HO + TeH: comparison with analogous reactions for HSe and HS.

The "gold standard" CCSD(T) method is adopted along with the correlation consistent basis sets up to aug-cc-pV5Z-PP to study the mechanism of the hydrogen abstraction reaction HTe + OH. The predicted geometries and vibrational frequencies for reactants and products are in good agreement with the available experimental results. With the ZPVE corrections, the transition state in the favorable pathway of this reaction energetically lies 1.

High thermoelectric performance of a ScSiTe monolayer at medium temperatures: an study.

Thermoelectric (TE) materials have attracted great attention in solving the problems in the waste heat field, while low figure of merit and poor material stability drastically limit their practical applications. In this work, a two-dimensional (2D) ScSiTe monolayer was systematically explored as a promising TE material methods. The results reveal that the ScSiTe monolayer possesses an indirect band gap with a rhombohedral crystal phase and exhibits excellent dynamic stability.

Thermoelectric performance enhancement of eco-friendly CuSe through incorporating CB.

We have prepared CuSe + wt% CB composites with = 0, 0.1, 0.3, 0.

Thermoelectric performance of ZrNX (X = Cl, Br and I) monolayers.

A low thermal conductivity and a high power factor are essential for efficient thermoelectric materials. The lattice thermal conductivity can be reduced by reducing the dimensions of the materials, thus improving the thermoelectric performance. In this work, the electronic, carrier and phonon transport and the thermoelectric properties of ZrNX (X = Cl, Br, and I) monolayers were investigated using density functional theory and Boltzmann transport theory.

Improved Thermoelectric Performance of Monolayer HfS by Strain Engineering.

Strain engineering can effectively improve the energy band degeneracy of two-dimensional transition metal dichalcogenides so that they exhibit good thermoelectric properties under strain. In this work, we have studied the phonon, electronic, thermal, and thermoelectric properties of 1T-phase monolayer HfS with biaxial strain based on first-principles calculations combined with Boltzmann equations. At 0% strain, the results show that the lattice thermal conductivity of monolayer HfS is 5.

Structure, stability, infrared spectra, and bonding of OH(HO) ( = 0, ±1) clusters: study combining the particle swarm optimization algorithm.

The various structural candidates of anionic, neutral, and cationic water clusters OHm(H2O)7 (m = 0, ±1) have been globally predicted by combining the particle swarm optimization method and quantum chemical calculations. Geometry optimization and vibrational analysis for the optimal structures were performed with the MP2/aug-cc-pVDZ method, and the energy profile was further refined at the CCSD(T)/CBS level. Special attention was paid to the relationships between configurations and energies, particularly the first solvation shell coordination number of OH- and OH.

Theoretical study for anisotropic responses of the condensed-phase RDX under shock loadings.

We have performed quantum-based molecular dynamics (MD) simulations in conjunction with multiscale shock technique (MSST) to investigate the initial chemical processes and the anisotropy of shock sensitivity of the RDX under shock loading applied along the different directions. The results show that there is a difference between x (or y)-direction and z-direction in the response to a shock wave velocity of 12 km/s. It was shown that detonation temperature and pressure in the z-direction lags behind that of x-direction (or y-direction).

Effect of Mn doping on electroforming and threshold voltages of bipolar resistive switching in Al/Mn : NiO/ITO.

We investigated the bipolar resistive switching (BRS) properties of Mn-doped NiO thin films by sol-gel spin-coating. As the Mn doping concentration increased, lattice constant, grain size and band gap were found to decrease simultaneously. Moreover, the electroforming voltages and threshold voltages were gradually reduced.

Structural, elastic, mechanical and thermodynamic properties of HfB under high pressure.

The present work aims to study the structural, elastic, mechanical and thermodynamic properties of the newly discovered orthorhombic structure HfB (denoted as -HfB hereafter) under pressure by the first-principles calculations. The obtained equilibrium structure parameters and ground-state mechanical properties were in excellent agreement with the other theoretical results. The calculated elastic constants and phonon dispersion spectra show that -HfB is mechanically and dynamically stable up to 100 GPa and no phase transition was observed.

Shock response of condensed-phase RDX: molecular dynamics simulations in conjunction with the MSST method.

We have performed molecular dynamics simulations in conjunction with the multiscale shock technique (MSST) to study the initial chemical processes of condensed-phase RDX under various shock velocities (8 km s, 10 km s and 11 km s). A self-consistent charge density functional tight-binding (SCC-DFTB) method was used. We find that the N-NO bond dissociation is the primary pathway for RDX with the NO groups facing (group 1) the shock, whereas the C-N bond scission is the dominant primary channel for RDX with the NO groups facing away from (group 2) the shock.

Pressure-induced metallization of condensed phase β-HMX under shock loadings via molecular dynamics simulations in conjunction with multi-scale shock technique.

The electronic structure and initial decomposition in high explosive HMX under conditions of shock loading are examined. The simulation is performed using quantum molecular dynamics in conjunction with multi-scale shock technique (MSST). A self-consistent charge density-functional tight-binding (SCC-DFTB) method is adapted.

Anisotropic responses and initial decomposition of condensed-phase β-HMX under shock loadings via molecular dynamics simulations in conjunction with multiscale shock technique.

Molecular dynamics simulations in conjunction with multiscale shock technique (MSST) are performed to study the initial chemical processes and the anisotropy of shock sensitivity of the condensed-phase HMX under shock loadings applied along the a, b, and c lattice vectors. A self-consistent charge density-functional tight-binding (SCC-DFTB) method was employed. Our results show that there is a difference between lattice vector a (or c) and lattice vector b in the response to a shock wave velocity of 11 km/s, which is investigated through reaction temperature and relative sliding rate between adjacent slipping planes.

Initial decomposition of the condensed-phase β-HMX under shock waves: molecular dynamics simulations.

We have performed quantum-based multiscale simulations to study the initial chemical processes of condensed-phase octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under shock wave loading. A self-consistent charge density-functional tight-binding (SCC-DFTB) method was employed. The results show that the initial decomposition of shocked HMX is triggered by the N-NO(2) bond breaking under the low velocity impact (8 km/s).