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Synthesis, Crystal and Electronic Structure of La 2 SiP 4
La 2 SiP 4 (mP-28, Z=4, Wyckoff sequence e 7 , space group P2 1 /c (No. 14), a=10.8230(6) Å, b=7.5208(4) Å, c=7.9189(4) Å, and β=105.389(2)°) which crystallizes in the La 2 CuS 4 structure type is reported here. Instead of isolated CuS 3 triangles bridged by disulfide anions, in the crystal structure of La 2 SiP 4 , one-dimensional zig-zag chains composed of SiP 4 tetrahedra connected by P–P bonds are present. Lanthanum cations fill the voids between the chains and are coordinated by either 9P or 8P+Si atoms. La2SiP4 is a narrow bandgap semiconductor with calculated and measured optical bandgaps of 0.35 eV and 0.85(1) eV, respectively.
Optimizing Excited-State Electronic-Structure Codes for Intel Knights Landing: A Case Study on the BerkeleyGW Software
We profile and optimize calculations performed with the BerkeleyGW code on the Xeon-Phi architecture. BerkeleyGW depends both on hand-tuned critical kernels as well as on BLAS and FFT libraries. We describe the optimization process and performance improvements achieved. We discuss a layered parallelization strategy to take advantage of vector, thread and node-level parallelism. We discuss locality changes (including the consequence of the lack of L3 cache) and effective use of the on-package high-bandwidth memory. We show preliminary results on Knights-Landing including a roofline study of code performance before and after a number of optimizations. We find that the GW method is particularly well-suited for many-core architectures due to the ability to exploit a large amount of parallelism over plane-wave components, band-pairs, and frequencies.
First-Principle Electronic Structure Study of Rhizoferrin and its Fe(III) Complexes
Abstract not provided
Structural, Electronic, Magnetic and Optical Investigations of Half-Heusler Compounds YZSb (Z = Cr, Mn): FP-LAPW Method
Half-Heusler compounds YZSb (Z = Cr, Mn) are theoretically explored in the framework of density functional theory (DFT). We have investigated a number of different properties with the help of the WIEN2k simulation package. Equilibrium lattice constants fall in the range 6.0–7.0 Å for both compounds. Elastic properties are also studied and it is found that the compound YCrSb is of brittle and YMnSb is of ductile nature as indicated by a number of parameters including Cauchy pressure, Pugh’s ratio and Poisson’s ratio. Electronically, these compounds are found to be half-metals as their spin-up states are semiconducting and hence 100% spin polarized at the Fermi level while spin-down states are conducting. The total magnetic moments are equal to 4μ{sub B} and 3.15μ{sub B} for YCrSb and YMnSb, respectively. The optical properties including dielectric function, reflectivity, refractive index, conductivity and absorption coefficients are calculated and discussed. Optical characteristics of the compounds hint that they are more active in the infrared region.
Magnetic Properties and Electronic Structure of Ni/C Multilayer Films
The magnetic properties of Ni/C multilayers were investigated using vibrating sample magnetometer and ferromagnetic resonance (FMR). Spin wave resonances were seen in FMR and the spin wave was found to be sustained through whole layers. The interlayer coupling constant was small pointing out a weak exchange coupling between Ni films through C spacers. The FMR linewidth, in parallel geometry, of the uniform mode decreases with the increase in Ni thickness from 30 to 300 Å which can be understood by considering interfacial effects. The magnetization decreases with decreasing Ni thickness due to the structural imperfections associated with the presence of Ni{sub 1−x}C{sub x} alloys at the interface. Density functional theory (DFT) has been performed to shed light on the decrease in magnetic moment at the interfaces.
Electronic Structure Effects in Transition Metal Surface Chemistry
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Optoelectronics: Optical properties and electronic structures of complex metal oxides
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How functional groups change the electronic structure of graphdiyne: Theory and experiment
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The effect of surface electronic structures of Au/TiO2 on sonophotochemical reactions
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A theoretical kinetic study of ĊH 3 + ṄH 2 : From electronic structure to NH 3 /CH 4 combustion modelling implications
Carbon–nitrogen interaction reactions play an important role in governing the reactivity of ammonia blended fuels. However, there remains uncertainties regarding their detailed reaction pathways and rate constants, hampering the development of high-fidelity chemical kinetic models. In this study, the kinetics of ĊH 3 + ṄH 2 , a key C–N interaction reaction in ammonia/methane blend combustion have been investigated. The potential energy surface has been explored using the high-level ANL0F method, yielding highly accurate stationary point energies that agree with ATcT values within 0.1 kcal mol –1 . Variable reaction coordinate transition state theory is used to treat the barrierless association and decomposition reaction channels, based on directly sampled radical-radical interaction energies at the CASPT2-F12(2e,2o)/cc-pVTZ-F12 level of theory. The minimum transitional mode numbers of states obtained are then coupled with the RRKM/master equation to calculate temperature- and pressure-dependent rate constants. Our a priori calculations capture available experimental measurements from the literature very well. The calculated rate constants have been incorporated into an NH 3 /CH 4 chemical kinetic model currently under development at the University of Galway. The effect of the updated kinetic data for ĊH 3 + ṄH 2 on model predicted NH 3 /CH 4 fuel reactivity is elucidated.
The effects of uniaxial and biaxial strain on the electronic structure of germanium
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Soft X-ray and electron spectroscopy to determine the electronic structure of materials for photoelectrochemical hydrogen production
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