104 research outputs found
Optical second harmonic generation in Yttrium Aluminum Borate single crystals (theoretical simulation and experiment)
Experimental measurements of the second order susceptibilities for the second
harmonic generation are reported for YAl3(BO3)4 (YAB) single crystals for the
two principal tensor components xyz and yyy. First principles calculation of
the linear and nonlinear optical susceptibilities for Yttrium Aluminum Borate
YAl3(BO3)4 (YAB) crystal have been carried out within a framework of the
full-potential linear augmented plane wave (FP-LAPW) method. Our calculations
show a large anisotropy of the linear and nonlinear optical susceptibilities.
The observed dependences of the second order susceptibilities for the static
frequency limit and for the frequency may be a consequence of different
contribution of electron-phonon interactions. The imaginary parts of the second
order SHG susceptibility chi_{123}^{(2)}(omega), chi_{112}^{(2)}(omega),
chi_{222}^{(2)}(omega), and chi_{213}^{(2)}(omega) are evaluated. We find that
the 2(omega) inter-band and intra-band contributions to the real and imaginary
parts of chi_{ijk}^{(2)}\l(omega) show opposite signs. The calculated second
order susceptibilities are in reasonably good agreement with the experimental
measurements.Comment: 16 pages, 11 figure
Electronic structure, linear, nonlinear optical susceptibilities and birefringence of CuInX2 (X = S, Se, Te) chalcopyrite-structure compounds
The electronic structure, linear and nonlinear optical properties have been
calculated for CuInX2 (X=S, Se, Te) chalcopyrite-structure single crystals
using the state-of-the-art full potential linear augmented plane wave (FP-LAPW)
method. We present results for band structure, density of states, and imaginary
part of the frequency-dependent linear and nonlinear optical susceptibilities.
We find that these crystals are semiconductors with direct band gaps. We have
calculated the birefringence of these crystals. The birefringence is negative
for CuInS2 and CuInSe2 while it is positive for CuInTe2 in agreement with the
experimental data. Calculations are reported for the frequency-dependent
complex second-order non-linear optical susceptibilities . The intra-band and
inter-band contributions to the second harmonic generation increase when we
replace S by Se and decrease when we replace Se by Te. We find that smaller
energy band gap compounds have larger values of in agreement with the
experimental data and previous theoretical calculations.Comment: 17 pages, 6 figure
Sulfide Oxide XZnSO (X =Ca or Sr) as Novel Active Photocatalytic Water Splitting Solar-to-Hydrogen Energy Conversion
Fotokatalytické, strukturní a transportní vlastnosti nově syntetizovaného sulfidu oxidu CaZnSO a SrZnSO jsou komplexně zkoumány výpočtem prvního a druhého principu za účelem vysvětlení "fotoexcitace" polovodičů, mechanismus stavu v CaZnSO a SrZnSO.The photocatalytic, structural and transport properties of the newly synthesized sulfide oxide CaZnSO and SrZnSO compounds are comprehensively investigated by means of first and second-principles calculation in order to explain the semiconductor's 'photoexcitation' state mechanism in CaZnSO and SrZnSO
Thermoelectric properties of TbFe2 and TbCo2 in C15-laves phase: Spin-polarized DFT plus U approach
Termoelektrické vlastnosti materiálů jsou závislé na pásové struktuře. Z prvních a druhých principielních výpočtů, jsme získali transportní vlastnosti pro spin- up a spin-down elektronů Lavesovy fáze TbFe2 a TbCo2 sloučenin.Thermoelectric properties of materials are intimately related to their electronic band structure. Com- bining first- and second-principles calculations, we have obtained the transport properties for the spin- up and spin-down electrons of the laves phase TbFe2 and TbCo2 compound
Quantum dots in photocatalytic applications: efficiently enhancing visible light photocatalytic activity by integrating CdO quantum dots as sensitizers
Sloučení fotokatalyzátoru s širokým optickým pásem s kvantovými tečkami CdO (QD) jako senzibilizátory je jedním z nejúčinnějších způsobů, jak zlepšit fotokatalytický výkon při ozařování viditelným světlemThe amalgamation of a wide optical band gap photocatalyst with visible-light-active CdO quantum dots (QDs) as sensitizers is one of the most efficient ways to improve photocatalytic performance under visible light irradiatio
Active photocatalytic water splitting solar-to-hydrogen energy conversion: Chalcogenide photocatalyst Ba2ZnSe3 under visible irradiation
Fotokatalytický výkon Ba2ZnSe3 je zkoumán teorií funkční hustoty. Zkoumání potvrzuje, že Ba2ZnSe3 vykazuje velkou birefringenci, značnou anizotropii v optické odezvě a absorpční okraj ve viditelné oblasti.The photocatalytic performance of Ba2ZnSe3 is investigated by means of density functional theory. The investigation confirms that Ba2ZnSe3 possesses large birefringence, considerable anisotropy in the optical response, and the absorption edge occurs in the visible region
Revealing the transport properties of the spin-polarized b0 -Tb2(MoO4)3: DFT U
Termoelektrické vlastnosti polarizované spin-polarizované b0-Tb2(MoO4)3 fáze se vypočítají pomocí prvních principů a druhých principů metod pro řešení poloklasických transportních rovnic Bloch-Boltzmann. Je zajímavé zdůraznit, že vypočtená elektronická struktura pásma odhalila, že b0-Tb2(MoO4)3 má parabolické pásy v blízkosti úrovně Fermi (EF).The thermoelectric properties of the spin-polarized b0-Tb2(MoO4)3 phase are calculated using first-principles and second-principles methods to solve the semi-classical Bloch-Boltzmann transport equations. It is interesting to highlight that the calculated electronic band structure reveals that the b0-Tb2(MoO4)3 has parabolic bands in the vicinity of the Fermi level (EF)
Electronic structure and optical properties of b-RbSm(MoO4)2 from spin polarization calculations: DFTþU
Prozkoumali jsme vliv začlenění spinové polarizace na mezery energetického pásma bRbSm (MoO4) 2. Výpočty prozkoumaly, že vzhled Sm-4f udává v minimálním vedení (CBM) spin-up případu významný vliv na vlastnosti půdního stavu b-RbSm (MoO4) 2.We explored the influence of the inclusion of spin polarization on the energy band gap of bRbSm(MoO4)2. Calculations explored that the appearance of Sm-4f states at the conduction band minimum (CBM) of the spin-up case causes a significant influence on ground state properties of b- RbSm(MoO4)2
Revealing the influence of the compression mechanism on the electronic structure and the related properties of CrF3
Vliv kompresního mechanismu na elementární buňky CrF3 je zkoumán pomocí funkční teorie hustoty. Experimentální parametry mřížky pod různými hodnotami tlaku, a to od běžného tlaku až do 9.12 GPa byly optimalizovány tak, aby došlo k uvolnění krystalických struktur.The influence of the compression mechanism on the unit cell of CrF3 is investigated by means of density functional theory. The experimental lattice parameters under different pressure values starting from the ambient pressure up to 9.12 GPa were optimized so as to relax the crystalline structures
Thermoelectric properties of the spin-polarized half-metallic ferromagnetic CsTe and RbSe compounds
Termoelektrické vlastnosti spin-polarizovaných polokovových feromagnetických sloučenin CsTe a RbSe jsou zkoumány na základě vypočítaných spin-polarizovaných elektronických pásových struktur. Vypočítané spin-polarizované elektronické pásové struktury ukazují, že obě sloučeniny vykazují polokovovou mezeru asi 0,06 (0,07) eV pro CsTe (RbSe).The thermoelectric properties of the spin-polarized half-metallic ferromagnetic CsTe and RbSe compounds are investigated based on the calculated spin-polarized electronic band structures. The calculated spin-polarized electronic band structures show that both compounds exhibit a half-metallic gap of about 0.06 (0.07) eV for CsTe (RbSe)
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