The Experts below are selected from a list of 563319 Experts worldwide ranked by ideXlab platform
Renata M Wentzcovitch - One of the best experts on this subject based on the ideXlab platform.
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accurate projected augmented wave paw datasets for rare earth elements re la lu
Computational Materials Science, 2014Co-Authors: Mehmet Topsakal, Renata M WentzcovitchAbstract:We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid State tests of generated datasets were performed on rare-earth nitrides. Through Density of State (DOS) and equation of State (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW + LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials. 2014 Elsevier B.V. All rights reserved.
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accurate projected augmented wave paw datasets for rare earth elements re la lu
arXiv: Materials Science, 2014Co-Authors: Mehmet Topsakal, Renata M WentzcovitchAbstract:We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid State tests of generated datasets were performed on rare-earth nitrides. Through Density of State (DOS) and equation of State (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials.
M Karabacak - One of the best experts on this subject based on the ideXlab platform.
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quantum chemical calculation electronic and topologic and experimental ft ir ft raman and uv analysis of isonicotinic acid n oxide
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015Co-Authors: Caglar Karaca, Ahmet Atac, M KarabacakAbstract:In this work, the molecular conformation, vibrational and electronic analysis of isonicotinic acid N-oxide (iso-NANO) were presented in the ground State using experimental techniques (FT-IR, FT-Raman and UV) and Density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. The geometry optimization and energies associated possible two conformers (Rot-I and Rot-II) were computed. The vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The obtained structures were analyzed with the Atoms in Molecules (AIMs) methodology. The computational results diagnose the most stable conformer of iso-NANO as the Rot-I form. Total Density of State (TDOS) and partial Density of State (PDOS) and also overlap population Density of State (OPDOS) diagrams analysis for the most stable conformer (Rot-I) were calculated using the same method. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated. As a result, the optimized geometry and calculated spectroscopic data show a good agreement with the experimental results.
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monomeric and dimeric structures analysis and spectroscopic characterization of 3 5 difluorophenylboronic acid with experimental ft ir ft raman 1h and 13c nmr uv techniques and quantum chemical calculations
Journal of Molecular Structure, 2014Co-Authors: M Karabacak, Ahmet Atac, Etem Kose, Abdullah M Asiri, Mustafa KurtAbstract:Abstract The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C 6 H 3 F 2 B(OH) 2 ) were investigated by FT-IR, FT-Raman UV–Vis, 1 H and 13 C NMR spectroscopic techniques. FT-IR (4000–400 cm –1 ) and FT-Raman spectra (3500–10 cm –1 ) in the solid phase and 1 H and 13 C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200–400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O–H⋯O hydrogen bonding have been discussed. 1 H and 13 C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent Density functional theory (TD-DFT) results complements with the experimental findings. Total and partial Density of State (TDOS and PDOS) and also overlap population Density of State (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.
Mehmet Topsakal - One of the best experts on this subject based on the ideXlab platform.
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accurate projected augmented wave paw datasets for rare earth elements re la lu
Computational Materials Science, 2014Co-Authors: Mehmet Topsakal, Renata M WentzcovitchAbstract:We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid State tests of generated datasets were performed on rare-earth nitrides. Through Density of State (DOS) and equation of State (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW + LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials. 2014 Elsevier B.V. All rights reserved.
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accurate projected augmented wave paw datasets for rare earth elements re la lu
arXiv: Materials Science, 2014Co-Authors: Mehmet Topsakal, Renata M WentzcovitchAbstract:We provide accurate projected augmented wave (PAW) datasets for rare-earth (RE) elements with some suggested Hubbard U values allowing efficient plane-wave calculations. Solid State tests of generated datasets were performed on rare-earth nitrides. Through Density of State (DOS) and equation of State (EoS) comparisons, generated datasets were shown to yield excellent results comparable to highly accurate all-electron full-potential linearized augmented plane-wave plus local orbital (FLAPW+LO) calculations. Hubbard U values for trivalent RE ions are determined according to hybrid functional calculations. We believe that these new and open-source PAW datasets will allow further studies on rare-earth materials.
Jeffrey G Snyder - One of the best experts on this subject based on the ideXlab platform.
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low effective mass leading to high thermoelectric performance
Energy and Environmental Science, 2012Co-Authors: Aaron D. Lalonde, Heng Wang, Jeffrey G SnyderAbstract:High Seebeck coefficient by creating large Density-of-States effective mass through either electronic structure modification or manipulating nanostructures is commonly considered as a route to advanced thermoelectrics. However, large Density-of-State due to flat bands leads to large transport effective mass, which results in a simultaneous decrease of mobility. In fact, the net effect of such a high effective mass is a lower thermoelectric figure of merit, zT, when the carriers are predominantly scattered by phonons according to the deformation potential theory of Bardeen–Shockley. We demonstrate that the beneficial effect of light effective mass contributes to high zT in n-type thermoelectric PbTe, where doping and temperature can be used to tune the effective mass. This clear demonstration of the deformation potential theory to thermoelectrics shows that the guiding principle for band structure engineering should be low effective mass along the transport direction.
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low effective mass leading to high thermoelectric performance
arXiv: Materials Science, 2011Co-Authors: Aaron D. Lalonde, Heng Wang, Jeffrey G SnyderAbstract:High Seebeck coefficient by creating large Density of State (DOS) around the Fermi level through either electronic structure modification or manipulating nanostructures, is commonly considered as a route to advanced thermoelectrics. However, large Density of State due to flat bands leads to large effective mass, which results in a simultaneous decrease of mobility. In fact, the net effect of high effective mass is a lower thermoelectric figure of merit when the carriers are predominantly scattered by acoustic phonons according to the deformation potential theory of Bardeen-Shockley. We demonstrate the beneficial effect of light effective mass leading to high power factor in n-type thermoelectric PbTe, where doping and temperature can be used to tune the effective mass. This clear demonstration of the deformation potential theory to thermoelectrics shows that the guiding principle for band structure engineering should be low effective mass along the transport direction.
Zhe Chuan Feng - One of the best experts on this subject based on the ideXlab platform.
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revealing the surface electronic structures of algan deep ultraviolet multiple quantum wells with lateral polarity domains
Photonics Research, 2020Co-Authors: Wei Guo, Li Chen, Yingda Qian, Moheb Sheikhi, Jason Hoo, Shiping Guo, Jianzhe Liu, Feras Alqatari, Zhe Chuan FengAbstract:We report on the carrier dynamic and electronic structure investigations on AlGaN-based deep-ultraviolet multiple quantum wells (MQWs) with lateral polarity domains. The localized potential maximum is predicted near the domain boundaries by first-principle calculation, suggesting carrier localization and efficient radiative recombination. More importantly, lateral band diagrams of the MQWs are proposed based on electron affinities and valance band levels calculated from ultraviolet (UV) photoelectron spectroscopy. The proposed lateral band diagram is further demonstrated by surface potential distribution collected by Kelvin probe microscopy and the Density-of-State calculation of energy bands. This work illustrates that lateral polarity structures are playing essential roles in the electronic properties of III-nitride photonic devices and may provide novel perspective in the realization of high-efficiency UV emitters.