In the present work,we investigate the structural,optoelectronic and thermoelectric properties of the YLi3X2(X = Sb,Bi) compounds using the full potential augmented plane wave plus local orbital(FP-APW+lo) method.The ...In the present work,we investigate the structural,optoelectronic and thermoelectric properties of the YLi3X2(X = Sb,Bi) compounds using the full potential augmented plane wave plus local orbital(FP-APW+lo) method.The exchangecorrelation potential is treated with the generalized gradient approximation/local density approximation(GGA/LDA) and with the modified Becke-Johnson potential(TB-mBJ) in order to improve the electronic band structure calculations.In addition,the estimated ground state properties such as the lattice constants,external parameters,and bulk moduli agree well with the available experimental data.Our band structure calculations with GGA and LDA predict that both compounds have semimetallic behaviors.However,the band structure calculations with the GGA/TB-mBJ approximation indicate that the ground state of the YLi3Sb2compound is semiconducting and has an estimated indirect band gap(Γ-L) of about 0.036 eV while the ground state of YLi3Bi2compound is semimetallic.Conversely the LDA/TB-mBJ calculations indicate that both compounds exhibit semiconducting characters and have an indirect band gap(Γ-L) of about 0.15 eV and 0.081 eV for YLi3Sb and YLi3Bi2respectively.Additionally,the optical properties reveal strong responses of the herein materials in the energy range between the IR and extreme UV regions.Thermoelectric properties such as thermal conductivity,electrical conductivity,Seebeck coefficient,and thermo power factors are also calculated.展开更多
By employing the spin resolved density functional theory, half-metallic character is investigated in Cs2NpBr6 having a K2PtCl6-type structure. The results precisely predict the half-metallic behavior of Cs2NpBr6. In s...By employing the spin resolved density functional theory, half-metallic character is investigated in Cs2NpBr6 having a K2PtCl6-type structure. The results precisely predict the half-metallic behavior of Cs2NpBr6. In spin-down state it presents an indirect band gap, while in spin-up channel it turns metallic. The structure optimization confirms the half-metallic nature in ferromagnetic configuration. The calculated magnetic moment is 3 μB toward which the main contributor is the Np atom.Furthermore, all the computed results are compared with the available experimental and theoretical values. According to the present analysis, we recommend Cs2NpBr6 for spintronic applications.展开更多
Data from spacecrafts suggest that space plasma has an abundance of suprathermal particles which are controlled by the spectral index κ when modeled on kappa particle velocity distribution. In this paper, considering...Data from spacecrafts suggest that space plasma has an abundance of suprathermal particles which are controlled by the spectral index κ when modeled on kappa particle velocity distribution. In this paper, considering homogeneous plasma, the effect of integer values of κ on the damping rate of an obliquely propagating magnetosonic(MS) wave is studied. The frequency of the MS wave is assumed to be less than ion cyclotron frequency, i.e.,iw(28)w. Under this assumption, the dispersion relation is investigated both numerically and analytically, and it is found that the real frequency of the wave is not a sensitive function of κ, but the imaginary part of the frequency is. It is also shown that for those values of κ where a large number of resonant particles participate in wave–particle interaction, the wave is heavily damped, as expected. The possible application of the results to the solar wind is discussed.展开更多
The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2(X = N,P,As,Sb,Bi).A full potential linearized augmented plane wave plus local orbitals method is used al...The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2(X = N,P,As,Sb,Bi).A full potential linearized augmented plane wave plus local orbitals method is used along with different exchange–correlation potentials to obtain the lattice constants,phonons,electronic,and optical properties of the Sr Mg2X2(X = N,P,As,Sb,Bi) Zintl compounds.A good agreement is achieved and our calculations are validated by previous experimental and theoretical data.All compounds have shown stable dynamical behavior with gamma centered longitudinal response having no imaginary frequencies.Electronic band structures reveal the semiconducting nature of the compounds.The Pnictogen(X)-p state contributed mainly in the valence band and the Sr-d state forms the conduction of the compounds.Relative charge transfer and low overlapping of the atomic densities indicates the preferable ionic bonding character of these materials.In the optical properties,real and imaginary parts of dielectric function,complex refractive index,birefringence,reflectivity,and optical conductivity are calculated.These compounds can be utilized in the optical and optoelectronic devices.展开更多
The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum plasma.Numerical results show that the energy flow speed decrease...The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum plasma.Numerical results show that the energy flow speed decreases with spin polarization parameter.It is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero asymtotically.It is observed that Bohm potential suppresses the energy flow speed.It is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential effect.However,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.展开更多
Methods capable of tuning the properties of van der Waals(vdW)layered materials in a controlled and reversible manner are highly desirable.Interfacial electronic properties of two-dimensional vdW heterostructure consi...Methods capable of tuning the properties of van der Waals(vdW)layered materials in a controlled and reversible manner are highly desirable.Interfacial electronic properties of two-dimensional vdW heterostructure consisting of silicene and indium selenide(InSe)have been calculated using density functional theory-based computational code.Furthermore,in order to vary the aforementioned properties,silicene is slid over a InSe layer in the presence of Li intercalation.On intercalation of the heterostructure,the buckling parameter associated with the corrugation of silicene decreases from 0.44A to 0.36A,whereas the InSe structure remains unaffected.Potential energy scans reveal a significant increase in the sliding energy barrier for the case of intercalated heterostructure as compared with the unintercalated heterostructure.The sliding of the silicene encounters the maximum energy barrier of 0.14 eV.Anisotropic analysis shows the noteworthy differences between calculated in-plane and out-of-plane part of dielectric function.A variation of the planar average charge density difference,dipole charge transfer and dipole moment have been discussed to elucidate the usability spectrum of the heterostructure.The employed approach based on intercalation and layer sliding can be effectively utilized for obtaining next-generation multifunctional devices.展开更多
The dispersion relations and Landau damping of Alfven waves in kinetic and inertial limits are studied in temperature anisotropic Cairns distributed plasma.In the case of kinetic Alfven waves(KAWs),it is found that th...The dispersion relations and Landau damping of Alfven waves in kinetic and inertial limits are studied in temperature anisotropic Cairns distributed plasma.In the case of kinetic Alfven waves(KAWs),it is found that the real frequency is enhanced when either the electron perpendicular temperature or the non-thermal parameter A increases.For inertial Alfven waves(IAWs),the real frequency is slightly affected by the electron temperature anisotropy and A.Besides the real frequency,the damping rate of KAWs is reduced when the electron perpendicular temperature or A increases.In the case of IAWs,the temperature anisotropy and A either enhance or reduce the damping rate depending upon the perpendicular wavelength.These results may be helpful to understand the dynamics of KAWs and IAWs in space plasmas where the non-Maxwellian distribution of particles are routinely observed.展开更多
基金the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP# 00
文摘In the present work,we investigate the structural,optoelectronic and thermoelectric properties of the YLi3X2(X = Sb,Bi) compounds using the full potential augmented plane wave plus local orbital(FP-APW+lo) method.The exchangecorrelation potential is treated with the generalized gradient approximation/local density approximation(GGA/LDA) and with the modified Becke-Johnson potential(TB-mBJ) in order to improve the electronic band structure calculations.In addition,the estimated ground state properties such as the lattice constants,external parameters,and bulk moduli agree well with the available experimental data.Our band structure calculations with GGA and LDA predict that both compounds have semimetallic behaviors.However,the band structure calculations with the GGA/TB-mBJ approximation indicate that the ground state of the YLi3Sb2compound is semiconducting and has an estimated indirect band gap(Γ-L) of about 0.036 eV while the ground state of YLi3Bi2compound is semimetallic.Conversely the LDA/TB-mBJ calculations indicate that both compounds exhibit semiconducting characters and have an indirect band gap(Γ-L) of about 0.15 eV and 0.081 eV for YLi3Sb and YLi3Bi2respectively.Additionally,the optical properties reveal strong responses of the herein materials in the energy range between the IR and extreme UV regions.Thermoelectric properties such as thermal conductivity,electrical conductivity,Seebeck coefficient,and thermo power factors are also calculated.
基金A.Laref was sponsored by the‘Research Center of Female Scientific and Medical Colleges’,Deanship of Scientific Research,King Saud University。
文摘By employing the spin resolved density functional theory, half-metallic character is investigated in Cs2NpBr6 having a K2PtCl6-type structure. The results precisely predict the half-metallic behavior of Cs2NpBr6. In spin-down state it presents an indirect band gap, while in spin-up channel it turns metallic. The structure optimization confirms the half-metallic nature in ferromagnetic configuration. The calculated magnetic moment is 3 μB toward which the main contributor is the Np atom.Furthermore, all the computed results are compared with the available experimental and theoretical values. According to the present analysis, we recommend Cs2NpBr6 for spintronic applications.
文摘Data from spacecrafts suggest that space plasma has an abundance of suprathermal particles which are controlled by the spectral index κ when modeled on kappa particle velocity distribution. In this paper, considering homogeneous plasma, the effect of integer values of κ on the damping rate of an obliquely propagating magnetosonic(MS) wave is studied. The frequency of the MS wave is assumed to be less than ion cyclotron frequency, i.e.,iw(28)w. Under this assumption, the dispersion relation is investigated both numerically and analytically, and it is found that the real frequency of the wave is not a sensitive function of κ, but the imaginary part of the frequency is. It is also shown that for those values of κ where a large number of resonant particles participate in wave–particle interaction, the wave is heavily damped, as expected. The possible application of the results to the solar wind is discussed.
基金Project supported by a grant from the"Research Center of Female Scientific and Medical Colleges",the Deanship of Scientific Research,King Saud UniversityYaseen M is thankful to Higher Education Commission(HEC)+1 种基金Pakistan for funding(Grant No.6410/Punjab/NRPU/R&D/HEC/2016)the support of the United States Government and the American people through the United States Agency for International Development(USAID)
文摘The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2(X = N,P,As,Sb,Bi).A full potential linearized augmented plane wave plus local orbitals method is used along with different exchange–correlation potentials to obtain the lattice constants,phonons,electronic,and optical properties of the Sr Mg2X2(X = N,P,As,Sb,Bi) Zintl compounds.A good agreement is achieved and our calculations are validated by previous experimental and theoretical data.All compounds have shown stable dynamical behavior with gamma centered longitudinal response having no imaginary frequencies.Electronic band structures reveal the semiconducting nature of the compounds.The Pnictogen(X)-p state contributed mainly in the valence band and the Sr-d state forms the conduction of the compounds.Relative charge transfer and low overlapping of the atomic densities indicates the preferable ionic bonding character of these materials.In the optical properties,real and imaginary parts of dielectric function,complex refractive index,birefringence,reflectivity,and optical conductivity are calculated.These compounds can be utilized in the optical and optoelectronic devices.
文摘The separate spin evolution quantum hydrodynamics(SSE-QHD)model is used to investigate the energy behavior for ion acoustic waves in degenerate quantum plasma.Numerical results show that the energy flow speed decreases with spin polarization parameter.It is also shown that it decreases with the increasing rate up to a certain range of wave number and then it goes to zero asymtotically.It is observed that Bohm potential suppresses the energy flow speed.It is also noticed that the energy flow speed deviates from the group velocity even in the absence of Bohm potential effect.However,the contribution of of Bohm poential effect in spin polarized plasma reduces the extent of deviation.
文摘Methods capable of tuning the properties of van der Waals(vdW)layered materials in a controlled and reversible manner are highly desirable.Interfacial electronic properties of two-dimensional vdW heterostructure consisting of silicene and indium selenide(InSe)have been calculated using density functional theory-based computational code.Furthermore,in order to vary the aforementioned properties,silicene is slid over a InSe layer in the presence of Li intercalation.On intercalation of the heterostructure,the buckling parameter associated with the corrugation of silicene decreases from 0.44A to 0.36A,whereas the InSe structure remains unaffected.Potential energy scans reveal a significant increase in the sliding energy barrier for the case of intercalated heterostructure as compared with the unintercalated heterostructure.The sliding of the silicene encounters the maximum energy barrier of 0.14 eV.Anisotropic analysis shows the noteworthy differences between calculated in-plane and out-of-plane part of dielectric function.A variation of the planar average charge density difference,dipole charge transfer and dipole moment have been discussed to elucidate the usability spectrum of the heterostructure.The employed approach based on intercalation and layer sliding can be effectively utilized for obtaining next-generation multifunctional devices.
文摘The dispersion relations and Landau damping of Alfven waves in kinetic and inertial limits are studied in temperature anisotropic Cairns distributed plasma.In the case of kinetic Alfven waves(KAWs),it is found that the real frequency is enhanced when either the electron perpendicular temperature or the non-thermal parameter A increases.For inertial Alfven waves(IAWs),the real frequency is slightly affected by the electron temperature anisotropy and A.Besides the real frequency,the damping rate of KAWs is reduced when the electron perpendicular temperature or A increases.In the case of IAWs,the temperature anisotropy and A either enhance or reduce the damping rate depending upon the perpendicular wavelength.These results may be helpful to understand the dynamics of KAWs and IAWs in space plasmas where the non-Maxwellian distribution of particles are routinely observed.