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Structural, electronic, and magnetic properties of ternary CdMAs2 (M = Sc, Ti, and V) compounds in the chalcopyrite structure have been studied using full-potential linearized augmented plane wave method based on density functional theory. We present a detailed study of electronic band structure, density of states, and magnetic moment of all three compounds within local spin density approximation and generalized gradient approximation. CdMAs2 compounds are derived from chalcopyrite structured CdGeAs2 with the substitution of transition metal (TM) atoms at Ge site. Negative values of formation energy signify that these materials are stable in chalcopyrite structure. Spin-polarized calculations show that the substitution of TM atoms at the group IV site influences the appearance of ferromagnetic state (FM) in CdScAs2 and CdVAs2 compounds. FM in CdScAs2 and CdVAs2 compounds is mainly due to the strong spin polarization of 3d states of M cations and 4p states of As anion. CdVAs2 also exhibits half metallic ferromagnetism with an integer magnetic moment of 1.00μB per formula unit. However, there is no effective spin-polarization of energy states at the Fermi level in CdTiAs2 compound and shows a non-magnetic behaviour.

First principles electronic structural calculation of full Heusler alloys Ir2YSi (Y= Sc to Ni) in the L21 (Cu2MnAl) and Xa (Hg2CuTi) structures have been studied using full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). From the total energy calculations, it has been observed that all these alloys are stable in L21 structure than Xa structure and also it is found that the alloys Ir2YSi (Y =V to Co) are ferromagnetically stable whereas the Ir2YSi (Y = Sc, Ti, and Ni) alloys are non-magnetic in their stable L21 structure. Spin polarized band structure calculations reveal that in Ir2YSi (Y= V to Co) alloys there is spin splitting of energy states around the Fermi level (EF) indicating ferromagnetism and moreover in Ir2YSi (Y = V, Cr, and Mn) alloys majority electrons have metallic behavior while minority electrons have semiconducting nature exhibiting half metallic ferromagnetic (HMF) nature. HMF property in Ir2YSi (Y = V, Cr, and Mn) alloys have been further confirmed from the integer total magnetic moment value of 3.0 µB, 4.0 µB and 5.0 µB per formula unit respectively. Spin polarization mainly arises from the interaction between 3d electrons of V/Cr/Mn atom and 5d electrons of Ir atom. This strong d-d hybridization between the transition atoms like Ir and V/Cr/Mn composing Heusler alloys is essential for the formation of gap at the EF between the valence and conduction bands. Our results show that Ir2YSi (Y= V, Cr, and Mn) will be suitable for ferromagnetic and spintronics applications.

The structural, electronic and magnetic properties of LiCaC and NaCaC compounds in half-Heusler structure have been studied using local density approximation (LDA) based on density functional theory (DFT). From the total energy calculation, it is found that the compounds LiCaC and NaCaC are stable in ferromagnetic phase. The spin-polarized electronic band structure and density of states of these compounds show that the minority spin channel has metallic nature and the majority spin channel has a semiconducting gap of 2.27 and 2.0 eV for LiCaC and NaCaC respectively, resulting in a stable half-metallic ferromagnetic (HMF) behavior with magnetic moment of 1 µB per formula unit. Analysis of density of states of these compounds indicates that the magnetic moment mainly originates from the strong spin-polarization of 2p like states of C and the hybridization between the C-2p like states and the Ca-3d like states. The robustness of half-metallicity against the lattice constant is also calculated. Presence of HMF in LiCaC and NaCaC compounds without any transition metal makes these compounds promising materials for spintronic applications.

The first-principles calculations using full potential linearized augmented plane wave method (FP-LAPW) was performed to determine the influence of dopants (N, P, As and Sb) on the electronic structure of MgS in the rock salt structure. In the present work both local spin density approximation (LSDA) and generalized gradient approximation (GGA) were used for exchange correlation potential functional. Among the group V elements N-doping alone induce half-metallic ferromagnetism in MgS host with a magnetic moment of 1.00 μB/f.u. Total energy calculations show that ferromagnetic state is more stable than non-magnetic state in all the compounds. The ground state properties such as equilibrium lattice constant, bulk modulus and bond length were calculated. The spin polarized electronic band structure, total and partial density of states calculations were carried out to study the origin of half-metallic ferromagnetism in these compounds. The difference between two exchange-correlation functions is also analyzed.

The first-principles calculation within density functional theory is used to study in detail the electronic structure and ground state properties of alkali-metal oxoargenates A4[Ag4O4] (A= Na, K and Rb). The total energies calculated within the atomic sphere approximation (ASA) were used to determine the ground state properties such as equilibrium lattice parameter, c/a ratio, bulk modulus and cohesive energy. The theoretically calculated equilibrium lattice constants values are in well agreement with the available experimental values. The electronic band structures, total and partial density of states are calculated. The result of electronic band structure shows that the KAgO and RbAgO are direct band gap semiconductors with their gap lying between the Γ-Γ points, whereas NaAgO is found to be an indirect band gap semiconductor with its gap lying between Z-Γ points.

Self-consistent scalar relativistic band structure calculations for AMO (A=Li, Na, K and Rb; M=Ag and Cu) compounds have been performed using the tight-binding linear muffin-tin orbital (TB-LMTO) method within the local density approximation (LDA). At ambient conditions, these compounds are found to crystallize in tetragonal KAgO-type structure with two different space group I-4m2 and I4/mmm. Nowadays, hypothetical structures are being considered to look for new functional materials. AMO compounds have stoichiometry similar to eight-electron half-Heusler materials of type I–I–VI which crystallizes in cubic (C1b) MgAgAs-type structure with space group F-43m. For all these compounds, by interchanging the positions of atoms in the hypothetical cubic structure, three phases (α, β and γ) are formed. The energy–volume relation for these compounds in tetragonal KAgO-type structure and cubic α, β and γ phases of related structure have been obtained. Under ambient conditions these compounds are more stable in tetragonal KAgO-type (I4/mmm) structure. The total energies calculated within the atomic sphere approximation (ASA) were used to determine the ground state properties such as equilibrium lattice parameters, c/a ratio, bulk modulus, cohesive energy and are compared with the available experimental results. The results of the electronic band structure calculations at ambient condition show that LiCuO and NaMO are indirect band gap semiconductors whereas KMO and RbMO are direct band gap semiconductors. At high pressure the band gap decreases and the phenomenon of band overlap metallization occur. Also these compounds undergo structural phase transition from tetragonal I-4m2 phase to cubic α-phase and transition pressures were calculated.

The first-principles study of the electronic structure and ferromagnetism of AeX (Ae=Be, Mg, Sr and Ba; X=Si, Ge and Sn) compounds have been performed in the ground-state CrB-type and hypothetical NaCl- and zinc blende-type structures by spin-polarization and non-spin-polarization calculations. The TBLMTO-ASA program was used for the purpose. In the CrB-type structure, all these compounds exhibit non-magnetic and metallic behavior. The calculations show that in the NaCl- and ZB-type structures BeSi, BeGe, BeSn, MgSi, MgGe and MgSn compounds are non-magnets whereas SrSi, SrGe, SrSn, BaSi, BaGe and BaSn compounds are ferromagnetic and metallic. Apart from this the ZB-type SrSi, SrGe, BaSi and BaGe compounds exhibit half-metallicity at their equilibrium volume with a magnetic moment of 2.0 μ B per formula unit. However, ZB-type SrSn and BaSn compounds are found to exhibit half-metallic property under expansion of volume. The magnetism arises mainly from the anion p-like states and partial involvement of cation d-like states. The ground state properties like equilibrium lattice parameters, bulk modulus, cohesive energy, magnetic moment, spin-flip-gap and majority spin band gap are calculated and compared with available results. The band structure and density of states are also presented. These materials will be useful for the study of p-electron magnetism and in spintronic devices.

Structural, electronic and magnetic properties of AeS0.875X0.125 (Ae = Mg, Ca and Sr; X = N, P, As and Sb) are investigated using density functional theory within the local spin density approximation and also generalized gradient approximation for the electronic exchange and correlation. The total energy calculation reveals that group V elements as dopants can induce stable ferromagnetic state in alkaline-earth sulfides. The variation of ground state properties such as equilibrium lattice constant, bulk modulus and bond length against atomic size of the dopants were investigated. The possibility of half-metallic ferromagnetism in AeS0.875X0.125 (Ae = Mg, Ca and Sr; X = N, P, As and Sb) were analyzed by electronic band structure and density of states calculations. The half-metallic gap, exchange energy, total and partial magnetic moments were calculated.

First-principles calculations based on the tight-binding linear muffin-tin orbital (TB-LMTO) method are performed to investigate the occurrence of spin polarization in the alkali-metal oxides (M2O) [M: Li, Na, K, Rb] in antifluorite (anti-CaF2-type) structure with non-magnetic sp (F, Cl, Br and I) dopants. The calculations reveal that non-magnetic substitutional doping at cation site can induce stable half-metallic ferromagnetic ground state in I2-VI compounds. Total energy calculations show that the antifluorite ferromagnetic state is energetically more stable than the antifluorite non-magnetic state at equilibrium volume. Ground state properties such as equilibrium lattice constant and bulk modulus were calculated. The calculated magnetic moment is found to be 2.00 μB per dopant atom.

Ab initio electronic structure calculations of hypothetical zinc-blende CaX (X =P , As, Sb) were performed using tight-binding linear muffin-tin orbital method. It was found that, these compounds are ferromagnets exhibiting half-metallicity. Total energy calculations show that the zinc blende ferromagnetic phase is more stable than the zinc-blende non-magnetic phase at equilibrium volume. Ground state properties such as equilibrium lattice constant, bulk modulus and cohesive energy were calculated. The calculated magnetic moment is found to be 1µB per formula unit for all these materials, which agrees well with the other theoretical results. On reducing the cell volume all these compounds are found to undergo a magnetic phase transition from zinc-blende ferromagnetic phase to zinc-blende non-magnetic phase.

Self-consistent scalar-relativistic band structure calculations have been performed to investigate the electronic structure and groundstate properties of alkali-metal oxides Li2O, Na2O, K2O and Rb2O in cubic antifluorite (anti-CaF2-type) structure using the linear muffin-tin orbital in its tight-binding representation (TB-LMTO) method. The calculated ground-state properties of these compounds such as equilibrium lattice parameter and bulk modulus are in agreement with the other theoretical calculations and experimental results. The results of the electronic structure calculations show that Li2O, K2O and Rb2O are indirect band gap semiconductors, whereas Na2O is found to be a direct band gap semiconductor. r 2007 Elsevier B.V. All rights reserved.

Electronic structure and magnetic properties of ZnMX2 (M=Sc, V, Mn and Fe; X= As and P) compounds in body centred tetragonal chalcopyrite structure have been investigated using first-principles calculations based on density functional theory (DFT) within the local spin density approximation (LSDA). The spin-polarized electronic band structure and density of states of all these compounds show that the spin-up electrons have metallic and the spin-down electrons have a semiconducting gap and the magnetic moment mainly originates from the strong spin polarization of 3d states of transition metal (M=Sc, V, Mn and Fe) atoms and p-like states of anion X (P and As) atoms.

The first principles tight-binding linear muffin-tin orbital method within the local density approximation (LDA) has been used to calculate the ground state properties structural phase transition and pressure dependence of the band gap of BeS, BeSe and BeTe. We have calculated the energy-volume relations for these compounds in the B3 and B8 phases. The calculated lattice parameters, bulk modulus and the pressure-volume relation were found to be in good agreement with the recent experimental results. We have also calculated the cohesive energy for them and they are consistent with the bulk modulus. The calculated B3 to B8 structural transition pressure for BeS, BeS and BeTe agree well with the experimental results. Our calculations show that these compounds are indirect band gap (Γ-X) semiconductors at ambient conditions. The calculated band gap values are found to be underestimated by 20–30% which is due to the usage of LDA. After the structural transition to the B8 phase BeS continues to be indirect band gap semiconductor and ultimately it becomes metallic above 100 GPa. BeSe and BeTe are metallic at B3 to B8 structural transition.

The first principles tight-binding linear muffin-tin orbital method within the local density approximation was used to calculate the electronic band structures and the total energies of CaS, CaSe and CaTe in NaCl-type and CsCl-type structures. The total energies were used to calculate the ground state properties such as lattice parameter, bulk modulus and the structural phase stability of these compounds. The transition pressure at which these compounds undergo the structural phase transition from NaCl-type to CsCl-type structure were calculated. The ground state properties, the transition pressures and the transition volumes are found to agree with the experimental and other theoretical results. The energy band gap at ambient condition in the NaCl-type structure were calculated and compared with the experimental results available for CaS and CaSe. For CaTe the experimental values of energy gap are not available. The valence-band width and the pressure coefficient of energy gap were also calculated. The closure of band gap at transition in CsCl structure for CaSe, and CaTe were explained by comparing the band structures of BaSe and SrSe in this phase.

The electronic band structure and the total energy of SrX (X=S, Se, Te) in NaCl-type and CsCl-type structures were studied using the tight binding linear muffin-tin orbital method. The calculated ground state properties such as lattice constant and bulk modulus are in agreement with the experimental values. The transition pressures and volumes also agree well with the experimental results. The energy gap at ambient conditions were calculated. The metallization pressures and volumes have also been estimated.

Here we present the electronic band structure calculations of CaFCl, SrFCl, BaFCl, BaFBr and BaFI performed using tight binding linear muffin-tin orbital method. The calculated ground state properties namely the lattice parameters, bulk moduli and the pressure-volume relations were found to be in good agreement with the experimental values. The electronic band structure of these compounds were calculated at ambient as well as in the high pressure region. The band gap values of these insulating systems were calculated and compared with available experimental values. At high pressure these compounds exhibit the interesting phenomenon of band overlap metallization.

Results of electronic band structure calculations for Fe 3 Pt performed using the linear muffin-tin orbital method in the tight binding representation are presented here. From the total energy calculations we find that at ambient conditions Fe 3 Pt is stable in the ferromagnetic phase, in agreement with the experimental results. Under compression Fe 3 Pt is found to undergo a magnetic transition to paramagnetic phase at a pressure of about 4 GPa, in excellent agreement with experimental observations.

A detailed description of the electronic band structures of MgS and MgSe were investigated using the tight binding linear muffintin orbital method. The calculations were done in the zinc blende (B3) and the NaCl-type (B1) structures. The calculated ground-state properties were found to be in agreement with the experimental values. Under compression both MgS and MgSe are found to undergo a structural phase transition from the B3 to the B1 structure at pressures of 377 and 317 kbar, respectively. At ambient conditions both MgS and MgSe are found to be indirect band gap semiconductors and exhibit the phenomenon of metallization at about 50% volume compression.

Alkaline-earth oxides (AeO; Ae = Mg, Ca and Sr) doped with group VII (F, Cl, Br and I) elements as promising spin-injector materials have been investigated by using first principles full-potential linearized augmented plane-wave method. The substitution of group VII elements turns the insulator host AeO into ferromagnetic and some of them exhibit half-metallic ferromagnetic property with an integer magnetic moment of 3.00 μ B /cell. The spin-resolved electronic band structure and density of states show that the Ae 0.875 M 0.125 O compounds exhibit spin-dependent transport properties, in which the conduction proceeds entirely via the minority spin state in F-doped AeO and through majority spin state in Cl, Br and I-doped CaO and SrO. The comparison of local spin density approximation and generalized gradient approximation is also carried out. The results show that the origin of ferromagnetism in Ae 0.875 M 0.125 O is attributed to the p-p hybridization interaction betwwn group VII elements and oxygen.

The results of first principles calculations of the electronic band structure and ground-state properties of alkali metal copper oxides A4[Cu4O4] (A = Li, Na, K and Rb) compounds are in tetragonal body centered structure with two different space groups I-4m2 and I4/mmm. The calculations have been carried out using the tight-binding linear muffin-tin orbital method within the local density approximation. The total energies calculated within the atomic sphere approximation where used to determine the ground-state properties such as equilibrium lattice parameters, c/a ratio, the bulk modulus and cohesive energy and these are found to be in good agreement with the available experimental values. The results of the electronic band structure calculations show that LiCuO, KCuO and RbCuO are indirect band gap semiconductors, whereas NaCuO is direct band gap semiconductor.

The band structure of BaSe in both Nad-type (Bl) and CsCl-type (B2) structures is determined using the self-consistent linear muffin-tin orbital method within the atomic sphere approximation (LMTO-ASA). In agreement with the earlier observations, the band gap is found to be indirect in both Bl and B2 structures. The calculated values of the band gaps are compared with the experimental values. From the ASA total energy calculations, the structural phase stability of BaSe is studied. At ambient conditions BaSe is found to be stable in the Bl structure. It undergoes a structural transition to the B2 structure at about 55 × 108 Pa, associated with a volume reduction of 14.3%. The equilibrium lattice constants for both Bl and B2 structures and the transition pressure are compared with earlier experimental results.

Here we report a theoretical calculation of the band structure and superconductivity of Se in the bcc phase. The energy band structure and the effect of pressure on the band structure is obtained by means of the Linear Muffin-Tin Orbital method within the atomic sphere approximation. The superconducting transition temperature (Tc) is calculated using McMillan's formula and we predict the value of Tc at 115.3 Gpa as 2.3 K. Further increase in presssure decreases the Tc values. The normal state electrical resistivity at 115.3 Gpa is 1.43 fl cm, with further increase in pressure the resistivity decreases, which is a typical behaviour of number of elemental metals under pressure.

The electronic structure and magnetic properties of calcium chalcogenides with the incorporation of nonmagnetic sp impurities (B, C and N) has been investigated based on first principles calculations. The calculations demonstrate that the substitution of C‐ and N‐ for chalcogen atom in calcium chalcogenides host can induce magnetism while B cannot induce spin polarization in CaS and CaSe except in CaTe. Furthermore C‐ and N‐ doped calcium chalcogenides is found to be half‐metallic with total magnetic moment of 2.00 μB and 1.00 μB per f.u. Density of states studies show that each C and N has spin‐polarized 2p states in the bandgap and hybridization between the p states of dopants and partial d states of Ca. This leads to half‐metallic ferromagnetism in these compounds. Our studies indicate that both C and N doping can enhance stable ferromagnetic state in host matrices. The electronic band structure calculations show, that hole mediated p‐p interaction mechanism is responsible for the formation of ferromag...

First principles calculations have been carried out to study the possibility of half‐metallic ferromagnetism in alkaline earth chalcogenides in the presence of 2p (B, C and N) elements. Half‐metallic ferromagnetism is found in alkaline earth chalcogenides by the substitution of C and N in anion site with total magnetic moment of 2.00 μB and 1.00 μB per formula unit respectively. Calculations show that B doping in alkaline chalcogenides does not lead to half‐metallic ferromagnetism. Analysis of the density of states and magnetic moment indicates that the half‐metallic ferromagnetism is mainly due to the spin‐polarization of p‐like states of dopants around the Fermi Level and the hybridization between the p‐like states of dopants and d‐like states of alkaline earth elements. Total energy calculations show that ferromagnetic state is more stable than nonmagnetic state.

We report here on the theoretical calculation of the band structure, superconductivity and structural stability of ZrN under high pressure. The effect of pressure on the energy band structure is determined using the self consistent linear muffin tin orbital (LMTO) method. The superconducting transition temperature T c is calculated using McMillan's formula. The calculated value of T c at ambient pressure is 9.666 K, which compares well with the experimental value of 10.700 K. The parameters needed to calculate T c are taken from LMTO band structure outputs. The T c values increase with increasing pressure. The total energy as a function of pressure is computed by reducing the atomic volume of ZrN for two structures, namely the NaCl-type and CsCl-type structures. The total energy studies show that ZrN is more stable in the NaCl-type structure than in the CsCl-type structure and there is no structural change up to 51.45 GPa.

We report a theoretical calculation of the band structure and superconductivity of Te in the BCC phase under pressure. The energy band structure and the effect of pressure on the band structure is obtained by means of the linear muffin-tin orbital method. The superconducting transition temperature ( T c ) is calculated using McMillan's formula. The calculated value of T c of Te in the BCC phase at 27.3 GPa is 7.16 K. Further increase in pressure decreases the T c values. The calculated value of resistivity at 27.3 GPa is 4.37 μΩ cm and further increase in pressure decreases the resistivity, which is a typical behaviour of a number of elemental metals under pressure.

A theoretical calculation of the band structure, electrical resistivity, and superconductivity of f.c.c. thorium under pressure is reported. The effect of pressure on the band structure is obtained by means of the linear muffin-tin orbital (LMTO) method. The superconducting transition temperature (Tc) is calculated using McMillan's as well as Allen-Dyne's modified formulae. The parameters necessary to calculate Tc are taken from the band structure outputs. The calculated values of Tc initially decrease with the increase in pressure up to 154 × 108 Pa and then begin to increase. The sudden increase in the value of Tc around 181 × 108 Pa is attributed to the change in the Fermi surface topology. The theoretically calculated values of resistivity initially decrease with increase in pressure up to 154 × 108 Pa and then begin to increase in accordance with the experimental results. The change in slope around 181 × 108 Pa may be due to a change in Fermi surface topology. The calculated values of ϱ are in correct trend with the experimental values.

The band structure and superconductivity of niobium nitride in the NaCl structure under pressure is theoretically calculated. The effect of pressure on the band structure is obtained by means of the self-consistent linear muffin-tin orbital method. The calculated equation of state is in good agreement with experimental results. The calculated value of the cell parameter is 0.4475 nm which is in agreement with the experimental value. McMillan's formula is used to calculate the values of the superconducting transition temperature (Tc). The parameters necessary to calculate Tc are taken from the band structure outputs. The theoretically calculated value of Tc under ambient condition is 14.594 K which compares well with the experimental value. Further increase in pressure increases the Tc values which may be due to sp d electron transfer from nonmetal to metal atom.

The total energy, energy bands, density of sates and half-metallic ferromagnetism of CaS0.875M0.125 (M = C, Si, Ge and Sn) have been studied using band structure calculation methods namely full potential linearized augmented plane wave (FP-LAPW) as well as tight binding linear muffin orbital (TB-LMTO) method. We find that within the generalized gradient approximation (GGA) all dopants induce half-metallic ferromagnetism in CaS, whereas in the case of local spin density approximation (LSDA) C- doping only induce half-metallicity in CaS. The calculated magnetic moment is found to be 2.00 μB per formula unit. The magnetism arises mainly from the p states of dopant atoms. The ground state properties such as lattice constant, total energy difference between non-magnetic and ferromagnetic state, total and partial magnetic moments have been calculated. Within the GGA calculation all dopants enhance the stability of ferromagnetic state.

We report a theoretical calculation of the band structure, electrical resistivity, and superconductivity of fcc thorium under pressure. The effect of pressure on the band structure is obtained by means of the linear muffin‐tin orbital (LMTO) method. The superconducting transition temperature (Tc) is calculated using McMillan’s as well as Allen‐Dynes modified formulas. The calculated values of Tc initially decreases with the increase in pressure up to 154 kbar and then begins to increase. The sudden increase in the value of Tc around 181 kbar is attributed to the change in Fermi surface topology. The theoretically calculated values of resistivity initially decreases with increase in pressure up to 154 kbar and then begins to increase in accordance with the experimental results.

The electronic structure and high pressure structural phase transition in thorium antimonide have been investigated using the tight binding LMTO method. We have calculated the total energies by reducing the cell volume for NaCl as well as CsCl structures using TBLMTO method. The total energy calculations reveal that ThSb undergoes a structural transition from NaCl to CsCl structure at 78 kbar. The calculated value of equilibrium cell volume and the cell volume at which phase transition occurs are found to have a good agreement with the experimental results.

The superconducting transition temperture and the electrical resistivity of Te in the bcc phase has been studied. The necessary parameters required to calculate Tc and Egp are taken from the band structure output of Linear muffin‐tin orbital method within the atomic sphere approximation. The superconducting transition temperature (Tc) is calculated using the McMillan’s formula. The calculated value of Tc of Te in the bcc phase at 27.3 GPa is 7.16 K. Further increase in pressure decreases the Tc values. The calculated value of resistivity at 27.3 GPa is 4.37 μΩcm and further increase in pressure decreases the resistivity, which is a typical behaviour of number of elemental metals under pressure.

Here we report the theoretical calculations of band structure and superconductivity of WC in the NaCl-type structure. The effect of pressure on the band structure is obtained using the linear muffin-tin orbital method. The superconducting transition temperature is calculated using McMillan's formula. The value ofTcat ambient conditions is 5.98 K which increases on compression. The increase inTcvalues with pressure may be due to continuous transfer of s electrons from the carbon site to d states of the tungsten site. The calculated value ofTcat ambient pressure and the positive pressure coefficient ofTcare in agreement with other transition metal carbides and nitrides.