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A single-junction solar cell with a direct and ideal photovoltaic forbidden bandgap value which maximizes the photon absorbed is needed for the diversity of solar energy conversion, as well as other optoelectronic applications. Here, the ternary calcium nitrides inverse perovskites Ca 3 PN, Ca 3 AsN, Ca 3 SbN, and Ca 3 BiN were investigated in the frame of Density Functional Theory (DFT). The principal novelty of this research essentially projects detailed information on the structural, elastic, electronic, transport, and optical properties of Ca 3 PN, Ca 3 AsN, Ca 3 SbN, and Ca 3 BiN compounds. The understudy compounds are founded to be thermodynamically and elastically stable at ambient pressure. The electronic properties demonstrate that the understudy compounds have direct semiconductor behaviors with the ideal solar cells forbidden band gaps values which overlap very well with the visible zone of the solar spectrum leading to these materials high absorption coefficients percentage of around 80%, low reflectance and transmittance along the visible zone. Besides, the inter-atomic bonds between M and surrounded atoms are ionic while Ca–N inter-atomic bond is polar covalent. Otherwise, the understudy compounds exhibit low recombination rates as well as low charge carrier's effective masses which boost the carrier mobility. In addition, with rising temperatures up to 1000 K, the Ca 3 PN, Ca 3 AsN, and Ca 3 SbN compounds undergo from n to p-type semiconductor behaviors while Ca 3 BiN shows a p-type semiconductor behavior. While the CSN compound has better characteristics in TE applications at 50 K where the ZT value is 80%. Accordingly, these out studying properties make the understudy compounds as new single-junction solar cells non-silicon based. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ab-initio calculations of LiNbO 3 using Wien2k code with GGA-PBE and HSE06 approximation. • calculate lattice thermal conductivity using Gibbs code and thermoelectric propreties using BoltzTraP simulation. • Study of structural, electronic and optical properties of lithium niobate (LiNbO 3) under compressive and tensile biaxial strain. • The biaxial strain affects value of the LiNbO 3 band gap retaining the semi-conductive nature. • Under compressive strain, the band gap increases but under tensile strain, the band gap decreases. The theoretical effects of biaxial strain on the structural, electronic, optical, and thermoelectric properties of LiNbO 3 were investigated using the Wien2k and BoltzTraP programs with the GGA approximation. The lattice thermal conductivity was calculated by the GIBBS code. We demonstrate that the bandgap value decreases and increase with the tensile and compressive strain respectively. The optical absorption and the optical conductivity of LiNbO 3 can be enhanced by applying tensile biaxial strain. The thermoelectric properties are also investigated. LiNbO 3 pure and under the biaxial strain is a p-type material. Our compounds are promising candidates for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulations, we studied phase diagrams and magnetic properties of a ferromagnetic/antiferromagnetic Ising nanoparticles assembly with the spin-1/2 core and spin-3/2 shell. The system consists of nanocubes with equivalent exchange couplings of core and shell. However, the exchange couplings between the adjacent spins of the core and shell and between the nanocubes are assumed to vary. Thus, the effects of the exchange couplings and the system size on the phase diagrams are analyzing. Interesting behaviors are found when investigating the critical behavior of the system, the magnetizations, the magnetic susceptibility and the hysteresis loops. The increase of the core/shell size involves that of the temperature one. In addition, the increase in positive exchange interactions between the spins of the core and shell, on the one hand, and between the nanocubes, on the other hand, also increase the critical temperature, which favors the stable phase (3/2, 1/2). • Monte Carlo Simulation is used to study the magnetic properties of an assembly of cubic Core-Shell nanoparticles. • Phases diagrams of critical temperature with the exchange interactions and anisotropy parameter have been studied. • The increase of positive J2/J1 and J4/J1 increase the critical temperature, favoring the stable phase (3/2, 1/2). • Core and Shell sizes, anisotropy and interactions parameters effects on Magnetic hysteresis cycles are given. • Dependent coercivity with sizes and parameters of interactions are found. [ABSTRACT FROM AUTHOR]

Using the extended Nagel-Schreckenberg (NS) model, we numerically study the impact of the heterogeneity of traffic with speed limit zone (SLZ) on the probability of occurrence of car accidents . SLZ in the heterogeneous traffic has an important effect, typically in the mixture velocities case. In the deterministic case, SLZ leads to the appearance of car accidents even in the low densities, in this region increases with increasing of fraction of fast vehicles . In the nondeterministic case, SLZ decreases the effect of braking probability in the low densities. Furthermore, the impact of multi-SLZ on the probability is also studied. In contrast with the homogeneous case [X. Li, H. Kuang, Y. Fan and G. Zhang, Int. J. Mod. Phys. C 25 (2014) 1450036], it is found that in the low densities the probability without SLZ is low than with multi-SLZ . However, the existence of multi-SLZ in the road decreases the risk of collision in the congestion phase. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new model for computer virus attacks and recovery at the level of information packets. The model we propose is based on one hand on the susceptible-infected (SI) and susceptible-infected-recovered (SIR) stochastic epidemic models for computer virus propagation and on the other hand on the time-discrete Markov chain of the minimal traffic routing protocol. We have applied this model to the scale free Barabasi-Albert network to determine how the dynamics of virus propagation is affected by the traffic flow in both the free-flow and the congested phases. The numerical results show essentially that the proportion of infected and recovered packets increases when the rate of infection and the recovery rate increase in the free-flow phase while in the congested phase, the number of infected (recovered) packets presents a maximum (minimum) at certain critical value of characterizing a certain competition between the infection and the recovery rates. [ABSTRACT FROM AUTHOR]

Using first principles calculations based on density functional theory (DFT), the electronic properties of SnO 2 bulk and thin films are studied. The electronic band structures and total energy over a range of SnO 2 -multilayer have been studied using DFT within the local density approximation (LDA). We show that changing the interatomic distances and relative positions of atoms could modify the band-gap energy of SnO 2 semiconductors. Electronic-structure calculations show that band-gap engineering is a powerful technique for the design of new promising candidates with a direct band-gap. Our results present an important advancement toward controlling the band structure and optoelectronic properties of few-layer SnO 2 via strain engineering, with important implications for practical device applications. [ABSTRACT FROM AUTHOR]

Two nonperturbative methods such as Monte-Carlo simulation (MC) and Transfer-Matrix Finite-Size-Scaling calculations (TMFSS) have been used to study the phase transition of the spin- 3 / 2 ​Blume–Emery–Griffiths model (BEG) with quadrupolar and antiferromagnetic next-nearest-neighbor exchange interactions. Ground state and finite temperature phase diagrams are obtained by means of these two methods. New degenerate phases are found and only second order phase transitions occur for all values of the parameter interactions. No sign of the intermediate phase is found from both methods. Critical exponents are also obtained from TMFSS calculations. Ising criticality and nonuniversal behaviors are observed depending on the strength of the second neighbor interaction. [ABSTRACT FROM AUTHOR]

Electronic and optical properties of silicon carbide nanosheet (2D monolayer) have been studied using full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) within WIEN2k package. The dielectric tensor is derived within the random phase approximation (RPA). The electronic structure and the optical properties of SiC nanosheet such as the dielectric function, reflectivity, absorption coefficient and optical conductivity are calculated for both perpendicular and parallel electric field polarizations. [ABSTRACT FROM AUTHOR]

Spontaneous polarization and magnetic properties of BiXO3 with X = Co, Fe, Mn, V, and Zn have been studied using the full-potential, linear augmented plane wave (FP-LAPW) method with GGA and mBJ implemented in the WIEN2K code. The investigation shows that BiXO3 with X = Co, Fe, Mn, and Zn is stable in the antiferromagnetic state while for BiVO3, the magnetic stability was shown in the ferromagnetic state. The calculation shows the existence of a charge transfer between p states of oxygen and d states of Co and Fe for X = Co and Fe. The existence of Co, Fe, Mn, and V makes BiXO3 a non-absorbent compound. However, for Zn, the structure behaves as an absorbent compound especially in the visible light. We note that the spontaneous polarization is calculated with Berry phase BI and was found very close and comparable with other works. [ABSTRACT FROM AUTHOR]

The linear optical and electronic properties of a monolayer graphene sheet are investigated using the Density Functional Theory within the Full Potential Linearized Augmented Plane Wave (FP-LAPW) formalism. Three approaches are used in this work: The Generalized Gradient Approximation (GGA), the Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ); implemented in WIEN2K code; and GW (Green function G and screened Coulomb interaction W ) implemented in Yambo code. The band gap of graphene with and without silicon doping and the effect of silicon on optical properties of graphene are calculated. The silicon doping opens the band gap of graphene and increases its optical conductivity. This material may be used in solar cell application. Other optical properties such as reflectivity and refractive index are also studied. [ABSTRACT FROM AUTHOR]

Electronic, optical properties and spontaneous polarization of cubic perovskite BaHfO have been investigated using the Full Potential Linear Augmented Plane Wave method, implemented in the Wien2k code, in connection with the Generalized Gradient Approximation (GGA) and the Tran-Blaha modified Becke-Johnson exchange potential approximation (TB-mBJ). The calculation of band structure and density of state using TB-mBJ approach shows that the gap of BaHfO is direct and equal to 5.9 eV which is in good agreement with the experiment data (6.0 eV), compared with GGA which gives 3.9 eV. The absorption coefficient α (ω) and the complex dielectric function ε (ω) are also investigated and predict that this compound can be effectively used in UV based optoelectronic devices. Furthermore, Using the PI approach, we can calculate the spontaneous polarization which is equal to 0.40 C/m and predict that is in the same order as the Ps of other perovskite. [ABSTRACT FROM AUTHOR]

Evaluating the properties of the magnetocaloric material regenerators is a crucial step in order to exploit them subsequently as the working substances in magnetic cooling devices. So, the main objective of this latter is to evaluate the electronic, magnetic properties as well as the magnetocaloric effect of HoN compound. To do so, a combination of DFT study and Monte Carlo simulations has been performed on HoN compound which undergoes a second-order ferromagnetic-paramagnetic phase transition. For this material, the temperature-dependent total magnetization, heat capacity and magnetic susceptibility have been calculated and are revealed that the curie temperature is acceptable concurrence with the experimental value. Furthermore, it was showed that under an applied magnetic field of 5T, the magnetocaloric effect (MCE) in regard to the maximum value of magnetic entropy change Δ S m a g m a x around its Curie temperature, agree well with the experimental one. Besides, the relative cooling power (RCP) values are found to be 28.5, 162.2 and 227 J. Kg−1 under different magnetic fields of 1,3 and 5T. All findings which are presented in the present work indicate that the large values of RCP and Δ S m a g m a x found in HoN are interesting for low-temperature magnetic refrigeration with excellent performance. • We have studied the magnetocaloric effect of the HoN compound. • We used the ab-initio calculations, the Monte Carlo simulation to study the magnetic properties. • A second-order ferromagnetic-paramagnetic phase transition about 15 K. • The magnetic moment and the exchange coupling interactions are calculated. [ABSTRACT FROM AUTHOR]

Evaluating the properties of the magnetocaloric material regenerators is a crucial step in order to exploit them subsequently as the working substances in magnetic cooling devices. So, the main objective of this latter is to evaluate the electronic, magnetic properties as well as the magnetocaloric effect of HoN compound. To do so, a combination of DFT study and Monte Carlo simulations has been performed on HoN compound which undergoes a second-order ferromagnetic-paramagnetic phase transition. For this material, the temperature-dependent total magnetization, heat capacity and magnetic susceptibility have been calculated and are revealed that the curie temperature is acceptable concurrence with the experimental value. Furthermore, it was showed that under an applied magnetic field of 5T, the magnetocaloric effect (MCE) in regard to the maximum value of magnetic entropy change Δ S m a g m a x around its Curie temperature, agree well with the experimental one. Besides, the relative cooling power (RCP) values are found to be 28.5, 162.2 and 227 J. Kg−1 under different magnetic fields of 1,3 and 5T. All findings which are presented in the present work indicate that the large values of RCP and Δ S m a g m a x found in HoN are interesting for low-temperature magnetic refrigeration with excellent performance. • We have studied the magnetocaloric effect of the HoN compound. • We used the ab-initio calculations, the Monte Carlo simulation to study the magnetic properties. • A second-order ferromagnetic-paramagnetic phase transition about 15 K. • The magnetic moment and the exchange coupling interactions are calculated. [ABSTRACT FROM AUTHOR]

In the present work, the structural, electronic, optical and thermoelectric properties of the ternary chalcopyrite compounds defined by ACuS 2 (A=Al, Ga, In) has been performed by density functional theory (DFT) combined with Boltzmann transport theory. Based on the generalized gradient (GGA) approach, the stability accompanied with the structural parameters of the studied structure compounds was evaluated. Furthermore, modified Becke-Johnson exchange potential (TB-mBJ) was adopted for the exchange correlation potential in order to prove the electronic and optical features of ACuS 2 (A=Al, Ga and In). The plotted density of state, band structure, distribution charge density of the ACuS 2 (A=Al, Ga and In) component, with dielectric function, reflectivity, Seebeck coefficients, electrical and thermal conductivity are obtained and discussed. Our result reveal, for electronic properties, that all components exhibit p-type semiconductor with direct band gap, with 1.51 eV for GaCuS 2. The chemical bonding analysis shows the presence of ionic bonding between Al/In/Ga and S. The calculated dielectric function and the absorption coefficient indicate that InCuS 2 followed by GaCuS 2 display an excellent absorption in the visible range with low reflectivity. The evaluated results are in excellent agreement with available experimental and theoretical data. The physical properties of the novel ACuS 2 (A=Al, Ga and In) compound show promising candidate toward photovoltaic, optoelectronic and thermoelectric device. [ABSTRACT FROM AUTHOR]

(Fe,Cu)-doped SnO2 nanocrystals was synthesized using the co-precipitation method. Magnetic Properties Measurement System (MPMS) revealed that for simple doping, Fe-doped SnO2 soft ferromagnetism at low temperature appears, while the ferromagnetic phase is stable at temperature higher than room temperature for Cu co-doping element. The ferromagnetism is significantly enhanced by the Cu addition to Fe-doped SnO2, according to the ZFC and FC magnetizations and the hysteresis loops. The evidences for the existence of superparamagnetism are characterized and high blocking temperature super-paramagnetism in (Fe,Cu)-doped SnO2 nanocrystals was observed. Based on first-principles calculations, we have investigated electronic structures and magnetic properties of Fe-doped SnO2 and (Fe,Cu)-doped SnO2 with and without defect with LDA and LDA-SIC approximations. The results suggest that the oxygen vacancies (VO) play a critical role in the activation of ferromagnetism in Fe doped SnO2. For (Fe,Cu)-doped SnO2 the results exhibit that Cu strongly influences on the magnetic properties of these doped systems which are in good agreement with the experimental observations. Electronic structure show that the presence of Cu promote the ferromagnetic bound magnetic polaron interaction through the carriers introduce by d (Cu). [ABSTRACT FROM AUTHOR]

Structural, magnetic and electronic properties of Sn 0.95 Fe 0.05 O 2 , Sn 0.90 Mn 0.05 Fe 0.05 O 2 and Sn 0.90 Cu 0.05 Fe 0.05 O 2 nanoparticles synthesized by co precipitation technique are studied in detail with experiments and ab initio calculations. High blocking temperature is observed in Sn 0.90 Mn 0.05 Fe 0.05 O 2 and Sn 0.90 Cu 0.05 Fe 0.05 O 2 nanoparticles. By ab intio calculation a direct correlation between the electron spin-orbital momentum (L–S) coupling and the superparamagnetic properties of SnO 2 based diluted magnetic semiconductor was observed. Our results suggest that it is possible to control the superparamagnetic properties through chemical composition. [ABSTRACT FROM AUTHOR]

Perovskite oxides have emerged as promising alternatives for photovoltaic devices due to their astonishing optoelectronic properties. Nevertheless, a density functional theory study was performed on the electronic, optical, and thermoelectric properties of ACoO 3 (A = Nd, Pr, and La) by TB-mBJ potentials. Based on the optimized structures, the observed results show that studied compounds display p-type semiconductor behavior with a bandgap of 1.95 eV, 1.08 eV, and 1.57 eV respectively. Hence, spherical charge density contours illustrate the ionic character of Nd/Pr/La/Co and O. The optical spectra are reported and discussed, the maximum absorption intensity for the LaCoO 3 is ∼20 × 104 cm around 400 nm. Furthermore, the figure of merit, the electrical and thermal conductivity of each compound are investigated by applying Boltzmann transport theory, the high mobility of carriers enhances the Seebeck coefficient and electrical conductivity of ACoO 3 (A = Nd, Pr, and La) materials. Our finding results make these materials favorable candidates for photovoltaic applications. • First-principles method was used to study the structural, electronic, optical and thermoelectric properties of oxide halide perovskite ACoO 3 (A = Nd, Pr or La). • The bandgap values of LaCoO 3 and NdCoO 3 are suitable for photovoltaic, optoelectronic devices. • The studied oxide halide perovskite ACoO 3 (A = Nd, Pr or La) show excellent light absorption in the visible range. • The NdCoO 3 exhibit high electrical conductivity. [ABSTRACT FROM AUTHOR]

The effects of Sulfur (S), Selenium (Se), or Tellurium (Te) doped SrHfO 3 (SHO) on the electronic, optical and photocatalytic properties have been investigated using Density Functional Theory, taking into account the intrinsic F-center defect (Ov) in oxide materials. The findings showed that the substitution of oxygen atoms by chalcogens impurities decreased the forbidden band of SHO effectively. Furthermore, there is a huge improvement of the absorption coefficient in the visible spectrum when chalcogens' impurities meet an Ov defect in SHO, especially when 8.333% of S or Se meet an Ov in SHO (S/Se@OII + Ov) due to the shifting of the Fermi level to the lowest unoccupied molecular orbital which caused the n-type semiconductor behavior giving rise to the enhancement of carrier concentrations. Otherwise, the positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital respect the limits necessary to split water except for 12.5% of Se or Te-doped SHO (Se/Te@OIII), 8.333% of Te doped SHO with the presence of an Ov (Te@OII + Ov), and 12.5% of Se or Te doped SHO with an Ov defect (Se/Te@OIII + Ov) structures. In addition, the formation energy confirms that all studied structures are thermodynamically stables. We believe that our research will serve as a base for future studies on SHO to be used as semiconductors for photovoltaic and photocatalytic hydrogen production from water splitting applications.1. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties of SnCoO nanocrystalline and diluted magnetic semiconductors have been investigated. This sample has been synthesized by co-precipitation route. Study of magnetization hysteresis loop measurements infer that the sample of SnCoO nanoparticle shows a well-defined hysteresis loop at 300 K temperature, which reflects its ferromagnetic behaviour. We confirmed the roomtemperature intrinsic ferromagnetic (FM) semiconductors by ab initio calculation, using the theory of the functional of density (DFT) by employing the method of Korringa-Kohn-Rostoker (KKR) as well as coherent potential approximation (CPA, explain the disorder effect) to systems. The ferromagnetic state energy was calculated and compared with the local-moment-disordered (LMD) state energy for local density approximation (LDA) and LDA-SIC approximation. Mechanism of hybridization and interaction between magnetic ions in SnCoO is also investigated. To explain the origin of ferromagnetic behaviour, we give information about total and atoms projected density of state functions. [ABSTRACT FROM AUTHOR]

Polycrystalline NiZnFeO ferrites have been prepared using the solid-state reaction technique. The structure of ferrite was measured using an X-ray diffractometer (XRD). It is shown that the structure of NiZnFeO ferrites is a single spinel structure. The magnetic properties of the samples were tested at room temperature by a superconducting quantum interference device (SQUID) to determine magnetic properties versus temperature and applied magnetic field. Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker method (KKR) combined with the coherent potential approximation (CPA), the ferromagnetic and half-metallic behaviors was observed with LDA (local density approximation) and LDA-SIC (local density approximation-self-interaction correction) approximation. [ABSTRACT FROM AUTHOR]

Converting solar energy into electrical or chemical energy is an effective solution to produce clean and less expensive energy. Based on this, this paper sheds new light on the neglected photovoltaic and photocatalytic hydrogen production from water splitting applications of lead-free calcium hafnate perovskite (CHO) by converting CHO from an insulator to a semiconductor by doping CHO with chalcogens. Moreover, the intrinsic oxygen vacancy (Vo) defect in oxide materials was taken into consideration in our calculations based on DFT using LDA + mBJ approximation. It was found that when CHO was doped with chalcogens impurities the forbidden band was decreased with the increase of chalcogens impurities concentrations in CHO, especially when Tellurium (Te) and Selenium (Se) substitutions meet a Vo defect in CHO due to the increases to its charge carries' mobility. Furthermore, when chalcogens impurities meet a Vo defect in CHO the edge's absorption extends in the visible spectrum which is a basic requirement for photovoltaic and photocatalyst devices. • This paper sheds new light on the neglected photovoltaic and photocatalytic hydrogen production from water splitting applications. • The intrinsic oxygen vacancy (Vo) defect in oxide materials was taken into consideration in our calculations based on DFT using LDA + mBJ approximation. • CHO was doped with chalcogens impurities the forbidden band was decreased with the increase of chalcogens impurities in CHO. • When chalcogens' impurities meet the presence of an oxygen vacancy defect in CHO the forbidden band was reduced. • When chalcogens impurities meet a Vo defect in CHO the edge's absorption extends in the visible spectrum. [ABSTRACT FROM AUTHOR]

The present study is carried out for investigating the half-metallic ferromagnetic behavior of C r and F e doped and co-doped G a N , respectively. To this end, ab-initio calculations using the Korringa-Kohn-Rostoker Green's function method coupled with the coherent potential approximation have been employed. In the background to make the study more useful, the first-principles computations were added and merged to the mean-field approximation and the Monte-Carlo simulation for the co-doped compound. Several variations were perceived in the results as in the bandgap energy, the energetic location of the transition-metal 3 d band and the X-ray absorption spectra. Besides, the stability of the system between the ferromagnetic and the spin-glass states is studied. Finally, we have integrated as input parameters in the classical Ising model by Monte-Carlo simulation, the exchange interactions obtained from ab-initio calculation, in order to confirm the half-metallic ferromagnetic states with high Néel temperature. • Study of half-metallic ferromagnetic behavior of Cr and Fe doped and co-doped GaN, respectively. • Ab-initio calculation and Monte Carlo Study (MCS) have been performed. • Half-metallic ferromagnetic states with high Neel temperature have been confirmed. [ABSTRACT FROM AUTHOR]

The electronic structure and magnetic properties of zinc-blende structure of (Ga,Co)N phase with N vacancy defects are investigated using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). The results show that (Ga,Co)N phase is ferromagnetically polarized with an enhancement of the polarization and that the electronic structure can be modified simply by changing the concentration of N vacancies. Moreover, the (Ga,Co)N with high density of N vacancies shows a drastic increase of the magnetic moment of cobalt in the parent GaN compound, to reach a maximum value of 1.7 μ/Co at 8 at.%, which is in good agreement with the experimental values reported in the literature. [ABSTRACT FROM AUTHOR]

Based on first-principles spin-density functional calculations, using the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA), we investigated the half-metallic ferrimagnetic properties of SnO codoped with Mn and Co impurities (Sn(Mn, Co)O) within the self-interaction-corrected (SIC) local density approximation. Mechanism of hybridization and interaction between magnetic ions in Sn(Mn, Co)O is investigated. The band structure model has been used to explain the strong ferrimagnetic interaction observed and the mechanism that stabilizes this state is proposed. [ABSTRACT FROM AUTHOR]

Abstract: On the basis of ab initio calculations (FPLO) and Monte Carlo Simulations (MCS) the phase diagrams and magnetic properties of the bulk perovskite LaMnO3 have been studied, using the Heisenberg model. It is shown, using ab initio calculations in the scalar relativistic scheme, that the stable phase is the antiferromagnetic A-type, which corresponds to ferromagnetic order of the manganese ions in the basal planes and antiferromagnetic order of these ions between these planes along the axis. Using the full four-component relativistic scheme, in order to calculate the magnetic anisotropy energy and constants, it is found that the favorable magnetic direction is the (010) axis. The transition temperatures and the critical exponents are obtained in the framework of Monte Carlo simulations. The magnetic anisotropy and the exchange couplings of the Heisenberg model are deduced from ab initio calculations. They lead, by using Monte Carlo simulations, to a quantitative agreement with the experimental transition temperatures. [Copyright &y& Elsevier]

First-principles study of the electronic and magnetic properties of zinc-blende and wurtzite structures of Fe-, Co-, and FeCo-doped ZnO is presented. It is found that after doping, this diamagnetic material becomes ferromagnetic and half-metallic. It is also shown that the half-metallicity may be obtained for ZnFeO, ZnCoO, and ZnFeCoO. The analysis of the spin density reveals that the ferromagnetic phase is due to the ferromagnetic coupling between the p-d states. The effects of Fe on the magnetic properties of ZB and WZ Fe-doped ZnO compound have been investigated with the GGA calculations. In order to understand the role of Fe atom in the ferromagnetism, the density of states both in the presence and absence of Co doping, were calculated. The obtained results show the presence of coupling between Co and Fe atoms through the spin-split impurity band exchange mechanism. More importantly, the calculations show that the magnetic moment changes sensitively with the type of structure of ZnO, zinc-blende, or wurtzite. A discussion by comparing the results obtained in this study and the experimental results reported in the literature of similar systems show a very good agreement. [ABSTRACT FROM AUTHOR]

This study focuses numerically on dynamics in two dimensions of vesicles in microcirculation. The method used is based on boundary integral formulation. This study is inspired by the behavior of red blood cells (RBCs) in the microvasculature. Red RBCs carry oxygen from the lungs and deliver it through the microvasculature. The shape adopted by RBCs can affect blood flow and influence oxygen delivery. Our simulation using vesicles (a simple model for RBC) reveals unexpected complexity as compared to the case where a purely unbounded Poiseuille flow is considered [Kaoui, Biros, and Misbah, Phys. Rev. Lett. 103, 188101 (2009)]. In sufficiently large channels (in the range of 100/µm; the vesicle size and its reduced volume are taken in the range of those of a human RBC), such as arterioles, a slipperlike (asymmetric) shape prevails. A parachutelike (symmetric) shape is adopted in smaller channels (in the range of 20 µm, as in venules), but this shape loses stability and again changes to a pronounced slipperlike morphology in channels having a size typical of capillaries (5-10 µm). Stiff membranes, mimicking malaria infection, for example, adopt a centered or off-centered snakelike locomotion instead (the denomination snaking is used for this regime). A general scenario of how and why vesicles adopt their morphologies and dynamics among several distinct possibilities is provided. This finding potentially points to nontrivial RBCs dynamics in the microvasculature. [ABSTRACT FROM AUTHOR]

• The Ab-initio calculations are performed to study the electronic and magnetic properties of Cu doped SnO 2. • The spin–orbit interaction is taken into account in Cu doped SnO 2 the LDA-SIC approximation. • The doped compound by Cu has an orbital moment which is a very rare characteristic for the transition metals. • The hyperfine magnetic field has been studied and and the link was made with the magnetic moment. In this work, we have shed light on the electronic and magnetic properties of Cu doped SnO 2 within the first-principles density functional theory. To treat the substitutional disorder we have exploited the Koringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA). Moreover, in order to express the exchange correlation potential we have used the local density approximation (LDA) and the self-interaction corrected (LDA-SIC). The intrinsic SnO 2 is a N-type semiconductor and has a direct forbidden gap at Г point which is equal to 2.45 eV. In addition, we have calculated the wavelength in vacuum corresponding to the undoped SnO 2 which is about 506,13 nm located in the visible range. These features are in great demand in optoelectronic applications. Besides, the doped compound by Cu has an orbital moment, a very rare characteristic especially in the presence of transition metals and not rare earths. We have also met the half-metallic behavior during doping with a low concentration of the Cu impurity which is highly sought after in spintronic devices. Finally, the hyperfine magnetic field B hf (KG) has also taken into consideration to determine which layer contributed the most and we have determined the link between the hyperfine field and the magnetic moment of Cu. [ABSTRACT FROM AUTHOR]

In this study, the effects of Sulfur (S), Selenium (Se), and Tellurium (Te) on the electronic and optical properties of LiNbO 3 were studied by using density functional theory (DFT) within Wien2k code based on the generalized gradient approximation (GGA-PBE). Analyses of the studied components revealed that the incorporation of chalcogens in LiNbO 3 effectively reduces the electronic band-gap and that varying the amount and the type of dopant can control the level of band-gap reduction. The band-gap is equal to 2.312 eV, 1.996 eV, and 0.924 eV for 11.11% S, Se, and Te doped LiNbO 3, respectively. For the pure LiNbO 3 , the band-gap is 3.544 eV. Moreover, the absorption is improved in the visible light (380–790 nm) and exceeds 105 cm−1 for Te doped-LiNbO 3. The dielectric constant at zero frequency (ε 1 (0)) is equal to 5.254 for LiNbO 3 and 8.531 for Te doped-LiNbO 3 : 11.11%. Optical conductivity and reflectivity are predicted and the results showed that increasing chalcogens concentration considerably improves the electrical conductivity. Comparisons between the three types of doping were also performed and the results indicated that Te would be the best substitute for oxygen in LiNbO 3; hence ensuring a promising and environmentally friendly new class of solar cells. [ABSTRACT FROM AUTHOR]

• The electronic structure of MnFe 2 O 4 were carried out using ab initio calculations. • Magnetic properties of MnFe 2 O 4 were carried out using Monte Carlo simulation. In this work, the electronic and magnetic properties of bulk spinel ferrite MnFe 2 O 4 were carried out using ab initio calculations and Monte Carlo simulation. The electronic properties as well as, the exchange coupling interactions and the magnetic anisotropy were calculated using Density functional theory. The obtained exchange couplings between nearest n eighbours (J AB = −21.8 K, J BB = 13.7 K and J AA = 8.6 K) and the magnetic anisotropy were used as input parameters in a classical Ising model to study the finite-temperature effects on the magnetic properties of bulk MnFe 2 O 4 with different size. It is shown that MnFe 2 O 4 has a magnetic transition around 559.26 K. [ABSTRACT FROM AUTHOR]

In this research, the effect of the control condition on the physical properties of Copper Oxide (CuO) thin-film has been successfully performed through the sol-gel procedure followed by spin coating technique on a glass substrate. Taguchi model was reported to find the most prominent factor on the deposits process of CuO thin coat with an L9 (33) orthogonal array. Besides, from XRD, we deduce the texture coefficient used to determine the S/N ratio. The selected influential parameters are: concentration of Copper (II) ions " Cu 2+ ", preheating temperature T P and the final heat-treatment temperature T f. The results showed that the obtained crystals exhibit a uniform and smooth morphology. The energy-dispersive X-ray spectroscopy (EDS) exploits the chemical composition of the prepared films. In addition, the Absorption spectra by UV–vis analysis of the obtained thin films reveal high absorbance in the visible range. In fact, the CuO films showed optimal gap energy of 1.47 eV. However, the prepared thin CuO films by the optimization of the Taguchi model lead to the enhancement of the optical properties and suggested that CuO thin film could be one of the potential solar cell absorbers in PV devices. • Optimize the optical properties of CuO thin-films by Taguchi design. • Morphological and optical properties were improved. • The critical factors are [Cu2+], T P and T f. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to evaluate the physical properties of Fe 3 S 4 material. To do so, Ab-initio calculations and Monte Carlo Simulations (MCS) by means of the mixed spin model have been used. Fe 3 S 4 compound is formed by two magnetic sub-lattices, one occupied the A tetrahedral with spin 5/2 and the other occupied by B octahedral with both spin 2 and 5/2. The density of states (DOS) has been investigated and confirmed that the compoundis a half metal. Further, the magnetization, susceptibility and specific heat curves have been determined for different sizes of the systemand fromwhich the values of critical exponentsand the critical temperature (T c) have been calculated. Besides, the temperature-dependent magnetization for different values of crystal field has been analyzed to provide an insight into the relation compensation phenomena and crystal field effect. [ABSTRACT FROM AUTHOR]

We use a cellular automata approach to describe the interactions of the immune system with the human immunodeficiency virus (HIV). We study the evolution of HIV infection, particularly in the clinical latency period. The results we have obtained show the existence of four different behaviours in the plane of death rate of virus–death rate of infected T cell. These regions meet at a critical point, where the virus density and the infected T cell density remain invariant during the evolution of disease. We have introduced two kinds of treatments, the protease inhibitors and the RT inhibitors, in order to study their effects on the evolution of HIV infection. These treatments are powerful in decreasing the density of the virus in the blood and the delay of the AIDS onset. [Copyright &y& Elsevier]

Inorganic metal halide perovskite has recently attracted great attention in the past few years. It's has shown great promise as evidenced by its semiconductor behaviors and direct band gap. In this paper, the electronic band structure, optical and transport properties of inorganic metal halide cubic perovskite CsBI 2 Br (B= Sn, Ge, Pb) have been investigated using the density functional theory (DFT). The results show that the compounds have a high absorption coefficient (over 105 cm-1) in visible range. Moreover, a considerable effect on the band-gap was found when we replaced the Lead on CsPbI 2 Br with Germanium or Tin; it goes from 1.85 eV for CsPbI 2 Br to 1.18 for CsGeI 2 Br and 1.07 eV for CsSnI 2 Br which are tunable band-gap for optoelectronics applications. However, in this study, it is clearly shown that CsGeI 2 Br is a good candidate for photovoltaics applications. [ABSTRACT FROM AUTHOR]

• The impact of Mn 2 O 3 secondary phase on the morphology, and physical properties of La 0.6 Ca 0.4 MnO 3 material was investigated. • When Mn 2 O 3 is mixed with the La 0.6 Ca 0.4 MnO 3 compound, SEM micrographs show an increase in the grains size. • The Mn 2 O 3 addition has no impact on the Curie temperature of the composites. • For 20% of Mn 2 O 3 , the refrigerant capacity can be enhanced by more than 20% when compared to that shown by the mother compound. Perovskite manganite (1−x)La 0.6 Ca 0.4 MnO 3 /xMn 2 O 3 (x = 0, 0.05. 0.1, 0.15, 0.20) composites were prepared by solid state reaction method. X-ray diffraction measurements were used to confirm the crystal structure and the average crystallite size of the samples. Their magnetic, magnetocaloric and heat capacity properties display a presence of second order magnetic phase transition at 260 K. The maximum magnetic entropy change was found to be 5.33 J/kgK for x = 0.1 of Mn 2 O 3 under 5 T. The relative cooling power (RCP) was found (235 J/kg) to largely exceed that reported in early works for a similar family of materials. In addition, the RCP of the mother alloy is enhanced by more than 20% under 32 kOe without affecting the Curie temperature that remains approximately constant close to 260 K. Our results suggest that the addition of Mn 2 O 3 could be useful for the enhancement of the LCMO refrigerant capacity without affecting the Curie temperature. [ABSTRACT FROM AUTHOR]

The theoretical effects of compressive strain on electronic, optical and thermoelectric properties for the cubic and tetragonal phases of BTO perovskite-type crystal have been investigated using Density Functional Theory (DFT). It was found that the compressive strain influences on the nature of the forbidden band of the cubic and tetragonal phases of BTO because by applying −2.3% or more of compressive strain, BTO becomes a semiconductor with a direct forbidden gap which eliminate the additional interaction in the CB which is a quite remarkable for photovoltaic devices. Furthermore, the values of forbidden gap width increase with increasing the percentage of compressive strain which shows the piezoelectric property of BTO. Moreover, the optical properties show that the pure and compressed BTO compounds are good materials for optical applications in both visible and UV spectrum. Additionally, the mobility of the holes grows with the compressive strain, which leads to increase the thermal and electrical conductivity of BTO. [ABSTRACT FROM AUTHOR]

• The CsPbBr 3 perovskite compound are studied using several concentration of Iodine. • The electronic and optical properties of this compound are investigated using ab initio calculation. • For different concentration of Iodine the gap value decreased from 2.16 eV to 1.43 eV. • The peak of absorption observed at the visible range for 33 % of Iodine doping. The halide perovskite CsPbBr 3 compound have a huge interest this last years as a promising perovskite for photovoltaic application due to their properties, as known in photovoltaic field the gap value is a major element who influences on the efficiency of panels. In this work, the electronic and optical properties of this compound are investigated using ab initio calculation. In addition, we applied a different percentage of Iodine doping in CsPbBr 3-x (x = 0%, 22 % and 33 % of I) to reduce the gap value. As a result the gap value decreased from 2.31 eV (0%) to 1.58 eV (33 %) of I-doping. Also, we had a peak at the visible range for the absorption showing at 33 % of I-doping. [ABSTRACT FROM AUTHOR]

The effects of Sulfur, Selenium or Tellurium-doped AZrO 3 (A = Ca, Ba and Sr) on electronic and optical properties have been investigated using ab initio calculations. We can confirm that the forbidden band decreases with the increase of chalcogens' concentration, especially for Te and Se doped AZrO 3. Moreover, the absorption and the optical conductivity in the visible spectrum were stimulated essentially for Te doped AZrO 3. Hence, Te would be the better substitute of O in Lead-Free Zirconate perovskites for a new class of promising eco-friendly solar cells. • The effects of S, Se or Te doped AZrO 3 on electronic and optical properties are investigated. • The forbidden band decreases with the increase of chalcogens' concentration, especially for Te and Se doped AZrO 3. • The absorption and the optical conductivity in the visible spectrum were stimulated essentially for Te doped AZrO 3. • The better substitute of O in Lead-Free Zirconate perovskites is a new class of promising eco-friendly solar cells. [ABSTRACT FROM AUTHOR]

The chalcogenide perovskite BaZrS 3 compound has a huge scientist interest recently due to their properties, and it is known as a new generation of photovoltaic semiconductor, with a specific gap value which is a major element who influences on the efficiency of panels. In this work, the electronic, optical and transport properties of perovskite BaZrS 3-x Se x compound doped with different concentrations of Se (x = 0%, 10%, 15% and 20%) are investigated using the density functional theory (DFT). It is found that the band gap values decreases by increasing the doping concentrations from 1.59 eV (for 0% of Se) to 1.35 eV (for 20% of Se). In addition, the optical properties indicate that the perovskite BaZrS 3 is a good absorber. Also, from the transport proprieties we observed that the BaZrS 3-x Se x compound is a p-type material. These results show that the BaZrS 3 compound doped with Se is a good candidate for photovoltaics applications. [ABSTRACT FROM AUTHOR]

In this paper, we reported a computational study of the 2-D nanomaterial (SnSi) as a possible new nanomaterial to be synthesized. This study is chiefly based on density functional theory calculation, which is implemented in the wien2k code. In fact, we calculated the electronic properties such as electronic band structures, band gaps, DOS, formation energy, and electrical conductivity of three types of monolayers Stana-Silicene; (SnSi, SnSi3, and SnSi7) with various concentrations (50%, 25%, and 12.5%) of the Sn and the Tin atoms. By computing the formation energy of these materials within various concentrations of the Sn atoms, we observed that the SnSi monolayer has more stability than SnSi3 and SnSi7. Another important result is that the electrical conductivity of SnSi depends on the concentrations of the Sn atoms. Indeed, it increases by increasing the concentration of the Sn atoms. By using various concentrations of the Tin atoms, we found out that all these nanomaterials behave as a semiconductor material within direct electronic band gaps. [ABSTRACT FROM AUTHOR]

The controversial materials using in solar cell, Copper-Indium-Gallium-Selenide (CIGS) is highly favorable for solar power systems, due to its large optical absorption coefficient, long term stability, low cost and high conversion efficiency. The electronic and optical properties of CuIn 1-x Ga x Se 2, are calculated using the density functional theory (DFT) implemented on Wien2k code with GGA + mBJ approximation, for different concentrations of Ga. Moreover, we compare the physical proprieties between CuInSe 2 CuIn 0.75 Ga 0.25 Se 2 , CuIn 0.50 Ga 0.50 Se 2, CuIn 0.25 Ga 0.75 Se 2 , CuGaSe 2 in the wavelength range. According to the picks obtained, we can affirm that the CIGS is a good candidate for photovoltaic applications, especially the CuIn 0.75 Ga 0.25 Se 2 because it's much more absorptive and productive, with an optical absorption that reaches 104 in visible range. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and magnetocaloric properties of metallic anti-perovskite Mn 3 InC compound are investigated using several theoretical methods such as: Ab-initio calculations and Monte Carlo simulations. Ternary manganese compounds Mn 3 InC have the cubic perovskite crystal structure, in which the Mn atoms are located at the face centered positions, the In atoms on the cubic corners and the C atoms at the body centered positions. Using the first principle calculations, the magnetic moment and the exchange coupling interactions values are calculated. The total magnetization and the susceptibility of this compound are determined. The critical temperature obtained is in good agreement with the experimental results. Obviously, the magnetic entropy change and relative cooling power (RCP) values for different external magnetic fields are obtained around T C. • The electronic structural, magnetic and magnetocaloric properties of metallic anti-perovskite compound Mn 3 InC are calculated. • These properties are determined using Ab-initio calculations and Monte Carlo simulations. • The total magnetization and the susceptibility of Mn 3 InC compound are determined. • The critical temperature obtained is in good agreement with the experimental results. • The magnetic entropy change and relative cooling power (RCP) for different external magnetic fields are obtained around T C. [ABSTRACT FROM AUTHOR]

Although extensive research has been devoted to treat virus propagation over decades, the effect of local routing protocols algorithms on it has been ignored. In this paper, we studied the effectiveness of local routing protocols and their additional algorithms; next-nearest neighbors (NNN) and restrictive queue- length algorithm (RQL) in term of robustness in computer virus spreading. It is found that, the local routing protocols without additional algorithms favor the virus spreading, due to the blind transmission of packets between source and destination, while in local routing protocols under (NNN) algorithm, the virus propagation is reduced remarkably. Moreover in local routing protocols under RQL, the virus propagation continues to be reduced more and more compared with NNN algorithm. Furthermore our results show that the node duplication avoidance (NDA) algorithm favors the computer virus spreading especially in sparse networks. Moreover, in comparison with shortest path (SP) and efficient path (EP) global routing strategies ,local routing protocols under the restrictive queue- length algorithm (RQL), the virus propagation is highly reduced and becomes unexpectedly comparable to the traditional shortest path strategy and overcomes the efficient path strategy which shows a high vulnerability and sensitivity to computer virus propagation. These results could be very helpful for network routing protocols designers to give more attention to local routing strategies and their additional algorithms in order to benefit from high capacity and high level of security plus the adaptability with the large scale free networks as the internet. [ABSTRACT FROM AUTHOR]

First-principle calculations have been performed to study the intermetallic alloys MgCoxNi1−x and intermetallic hydrides MgCoxNi1−xH3 using full-potential local orbital (FPLO). The electronic structure of Mg-hydride-based alloys has been elaborated to predict further modifications which destabilize the corresponding hydrides. In this paper, we have demonstrated that the insertion of Co element plays a crucial role in the stability of doped intermetallic hydrides (MgCo0.50Ni0.50H3, MgCo0.75Ni0.25H3 and MgCo0.875Ni0.125H3), by enhancing the hydrogen storage capacities which becomes around 3.488 wt%, also the desorption temperature has improved significantly. Therefore, the mixture between Co and Ni plays an important role in the hydrogen uptake mechanism in the target intermetallic matrix. [ABSTRACT FROM AUTHOR]

SnO2:TM (V, Cr, Mn and Fe) based dilute magnetic semiconductors are investigated within self-interaction-corrected local density approximation (LSDA-SIC) from first-principles calculation. LSDA-SIC results are compared with the calculated ones within standard LSDA, the stable magnetic state of the system is evaluated by comparing the total energies of ferromagnetic state and spin-glass state. The Ferromagnetic and half metallic behaviors was observed and conformed with the local-moment-disordered state energy for LSDA and LSDA-SIC approximation in [Sn 0.95 TM 0.05 (V, Cr, Mn and Fe)]O2. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions. [ABSTRACT FROM AUTHOR]

Widely regarded as an interesting model system for studying flow properties of blood, vesicles are closed membranes of phospholipids that mimic the cytoplasmic membranes of red blood cells. In this study we analyze the rheology of a suspension of vesicles in a confined geometry: the suspension, bound by two planar rigid walls on each side, is subject to a shear flow. Flow properties are then analyzed as a function of shear rate γ, the concentration of the suspension ϕ, and the viscosity contrast λ = ηin/ηout, where ηin and ηout are the fluid viscosities of the inner and outer fluids, respectively. We find that the apparent (or effective viscosity) of the suspension exhibits both shear thinning (decreasing viscosity with shear rate) or shear thickening (increasing viscosity with shear rate) in the same concentration range. The shear thinning or thickening behaviors appear as subtle phenomena, dependant on viscosity contrast λ. We provide physical arguments on the origins of these behaviors. [ABSTRACT FROM AUTHOR]