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

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)

Linear and nonlinear optical susceptibilities of bilayer graphene

The linear and nonlinear optical susceptibilities of bilayer pristine graphene (BLPG) and H2S single molecule adsorbed at three different sites on a single graphene sheet of BLPG are calculated to obtain further insight into the electronic properties. Calculations show that the adsorption of H2S on the bridge and top sites open a gap around the Fermi level, while adsorption of H2S on the hollow site closes the energy gap, resulting in significant changes in the linear and nonlinear optical susceptibilities. This is attributed to the fact that the adsorbed H2S onto a single graphene sheet of BLPG cause significant changes in the electronic structure. The calculated linear optical susceptibilities show a huge anisotropy confirming that the graphene has unusual and interesting optical properties. We find that the absorption spectrum of graphene is quite flat extending from 300-2500 nm with an absorption peak in the UV region (similar to 270 nm), which is in excellent agreement with the experimental data. The pristine graphene shows a strong saturable absorption because of a large absorption and Pauli blocking. We have calculated the nonlinear optical susceptibilities of BLPG and the three configurations and found that they possess a huge second harmonic generation. We have also calculated the microscopic hyperpolarizability, beta(ijk), for BLPG

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)

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