Linear Muffin-tin Orbital Calculations Research Articles

Structural order-disorder in CaFe6Ge6 and Ca1-xCo6Ge6

Ternary alkaline earth transition metal germanides CaFe6Ge6 and Ca1-xCo6Ge6 have been synthesized and investigated. Depending on synthesis paths, different modifications have been found, all ordering variants of stuffed CoSn-type: CaFe6Ge6 with Y0.5Co3Ge3-type (P6/mmm, a = 5.1077(1) Å, c ​= ​4.0636(2) Å), MgCo6Ge6-type (P6/mmm, a = 5.1017(1) Å, c ​= ​8.1080(5) Å) or TbFe6Sn6-type (Cmcm, a = 8.150(2) Å, b ​= ​17.698(4) Å, c ​= ​5.116(1) Å) and Ca1-xCo6Ge6 with Y0.5Co3Ge3-type (P6/mmm, a = 5.1016(2) Å, c ​= ​3.9286(3) Å) or ScFe6Ga6-type (Immm, a = 8.830(2) Å, b ​= ​5.100(1) Å, c ​= ​7.855(2) Å). The main structural motif in Ca(Fe/Co)6Ge6 is Kagomé layers of Fe/Co atoms alternating with honeycomb layers of Ge atoms, where the hexagonal channels are filled with Ca atoms and Ge–Ge dumbbels. Up to date, calcium is the largest guest atom in this 166 structural family. The crystal chemistry and chemical bonding are discussed in terms of linear muffin-tin orbital band structure calculations and a topological analysis using the electron localization function.

The Pseudopotential Approach within Density-Functional Theory: The Case of Atomic Metallic Hydrogen

Internal energies, enthalpies, phonon dispersion curves, and superconductivity of atomic metallic hydrogen are calculated. The standard use of pseudopotentials in density-functional theory are compared with full Coulomb-potential, all-electron linear muffin-tin orbital calculations. Quantitatively similar results are found as far as internal energies are concerned. Larger differences are found for phase-transition pressures; significant enough to affect the phase diagram. Electron–phonon spectral functions α2F(ω) also show significant differences. Against expectation, the estimated superconducting critical-temperature Tc of the first atomic metallic phase I41/amd (Cs-IV) at 500 GPa is actually higher.

A new monoclinic structure type for ternary gallide MgCoGa2.

The crystal structure of MgCoGa2 (magnesium cobalt digallide) was solved by direct methods and refined in two space groups as P21/c (standard choice) and P21/n (non-standard choice). The refined lattice parameters for the standard choice are a= 5.1505 (2), b= 7.2571 (2), c= 8.0264 (3) Å and β= 125.571 (3)°, and for the non-standard choice are a= 5.1505 (2), b= 7.2571 (2), c= 6.5464 (2) Å and β= 94.217 (3)°. All parameters for MgCoGa2 refined to R1= 0.027 and wR2= 0.042 using 594 reflections. The crystal structure peculiarities of this compound are discussed. Particular attention has been given to relationships with other similar structures, such as YPd2Si and Fe3C. Crystallographic analysis, together with linear muffin-tin orbital electronic structure calculations, reveals the presence of three-dimensional polyatomic nets with partial covalent bonding between the Ga atoms.

New quaternary selenides Tl4Sb8Sn5Se24 and Tl5Sb2Sn4Se14−x (x=0.5)

Abstract Synthesis, structural characterization and chemical bonding peculiarities of two new quaternary selenides of the Tl4Sb8Sn5Se24 and Tl5Sb2Sn4Se14−x (x = 0.5) are reported. The crystal structures of these compounds were determined by single crystal X-ray diffraction analysis. The Tl4Sb8Sn5Se24 phase is a new structure type and crystallizes in the triclinic P 1̅ space group (a = 7.9061(13) Å, b = 13.9035(16) Å, c = 21.4665(17) Å, α = 80.058(8)°, β = 84.727(10)°, γ = 73.542(12)°, wR 2 = 0.0258, 8200 F 2 values, 373 variables). The Tl5Sb2Sn4Se14−x (x = 0.5) phase represents a new structure type with a tetragonal unit cell (P 4/mbm, a = 8.1570(10) Å, c = 21.946(3) Å, wR 2 = 0.0346, 1953 F 2 values, 44 variables). Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals that both structures we conform to the concept of Zintl-Klemm and exhibit semiconductor properties.

Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions

We report a combined experimental and theoretical study of the melting curve and the structural behavior of vanadium under extreme pressure and temperature. We performed powder x-ray diffraction experiments up to 120 GPa and 4000 K, determining the phase boundary of the bcc-to-rhombohedral transition and melting temperatures at different pressures. Melting temperatures have also been established from the observation of temperature plateaus during laser heating, and the results from the density-functional theory calculations. Results obtained from our experiments and calculations are fully consistent and lead to an accurate determination of the melting curve of vanadium. These results are discussed in comparison with previous studies. The melting temperatures determined in this study are higher than those previously obtained using the speckle method, but also considerably lower than those obtained from shock-wave experiments and linear muffin-tin orbital calculations. Finally, a high-pressure high-temperature equation of state up to 120 GPa and 2800 K has also been determined.

Multiple Electronic Components and Lifshitz Transitions by Oxygen Wires Formation in Layered Cuprates and Nickelates

There is growing compelling experimental evidence that a quantum complex matter scenario made of multiple electronic components and competing quantum phases is needed to grab the key physics of high critical temperature (Tc) superconductivity in layered cuprates. While it is known that defect self-organization controls Tc, the mechanism remains an open issue. Here we focus on the theoretical prediction of the multiband electronic structure and the formation of broken Fermi surfaces generated by the self-organization of oxygen interstitials Oi atomic wires in the spacer layers in HgBa2CuO4+δ, La2CuO4+δ and La2NiO4+δ, by means of self-consistent Linear Muffin-Tin Orbital (LMTO) calculations. The electronic structure of a first phase of ordered Oi atomic wires and of a second glassy phase made of disordered Oi impurities have been studied through supercell calculations. We show the common features of the influence of Oi wires in the electronic structure in three types of materials. The ordering of Oi into wires leads to a separation of the electronic states between the Oi ensemble and the rest of the bulk. The wire formation first produces quantum confined localized states near the wire, which coexist with, Second, delocalized states in the Fermi surface (FS) of doped cuprates. A new scenario emerges for high Tc superconductivity, where Kitaev wires with Majorana bound states are proximity-coupled to a 2D d-wave superconductor.

Synthesis and crystal structure of new compounds from the Y–Mg–Ni system

Abstract The synthesis, structural characterization, and chemical bonding peculiarities of new intermetallic compounds from Y–Mg–Ni ternary system are reported herein. The crystal structures of these compounds were determined by single-crystal and X-ray powder diffraction analysis. Three ternary compounds were studied: Y2Mg11Ni2 [own structure type, monoclinic, Pearson Symbol mS30, Space Group C2/m, a=18.969(4), b=3.6582(7), c=11.845(2) Å, β=125.07(3)°], Y4Mg3Ni2 [Ru4Al3B2 structure type, tetragonal, P4/mmm, tP18, a=10.8668(2), c=3.59781(12) Å] and YMgNi [MoAlB structure type, orthorhombic, Cmcm, a=3.6713(4), b=17.708(3), c=3.9583(5) Å]. New compositions of Y1− x Mg x Ni4 and Y5− x Mg24+ x solid solutions were detected: YMg0.86(1)Ni4.14(1) [SnMgCu4 structure type, cubic, F4̅3m, cF24, a=7.0747(6) Å] and Y4.28(1)Mg24.72(1) [Ti5Re24 structure type, cubic, I4̅3m, cI58, a=11.2655(11) Å]. The crystal structure peculiarities of these compounds are discussed. A particular attention has been given to Y2Mg11Ni2 and its relations with other Mg-containing compounds. Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals the presence of [Y2Ni4@Mg20] and [Y4Ni2@Mg18] clusters in Y2Mg11Ni2 phase. For Y4Mg3Ni2 the formation of the Ni–Mg nets was observed, while the Y atoms form a monolayer.

Effect of MultiSubstitution on the Thermoelectric Performance of the Ca11-xYbxSb10-yGez (0 ≤ x ≤ 9; 0 ≤ y ≤ 3; 0 ≤ z ≤ 3) System: Experimental and Theoretical Studies.

The Zintl phase solid-solution Ca11-xYbxSb10-yGez (0 ≤ x ≤ 9; 0 ≤ y ≤ 3; 0 ≤ z ≤ 3) system with the cationic/anionic multisubstitution has been synthesized by molten Sn metal flux and arc-melting methods. The crystal structure of the nine title compounds were characterized by both powder and single-crystal X-ray diffractions and adopted the Ho11Ge10-type structure with the tetragonal space group I4/mmm (Z = 4, Pearson Code tI84). The overall isotypic structure of the nine title compounds can be illustrated as an assembly of three different types of cationic polyhedra sharing faces with their neighboring polyhedra and the three-dimensional cage-shaped anionic frameworks consisting of the dumbbell-shaped Sb2 units and the square-shaped Sb4 or (Sb/Ge)4 units. During the multisubstitution trials, interestingly, we observed a metal-to-semiconductor transition as the Ca and Ge contents increased in the title system from Yb11Sb10 to Ca9Yb2Sb7Ge3 (nominal compositions) on the basis of a series of thermoelectric property measurements. This phenomenon can be elucidated by the suppression of a bipolar conduction of holes and electrons via an extra hole-carrier doping. The tight-binding linear muffin-tin orbital calculations using four hypothetical structural models nicely proved that the size of a pseudogap and the magnitude of the density of states at the Fermi level are significantly influenced by substituting elements as well as their atomic sites in a unit cell. The observed particular cationic/anionic site preferences, the historically known abnormalities of atomic displacement parameters, and the occupation deficiencies of particular atomic sites are further rationalized by the QVAL value criterion on the basis of the theoretical calculations. The results of SEM, EDS, and TGA analyses are also provided.

First-Order Phase Transition in BaNi2Ge2 and the Influence of the Valence Electron Count on Distortion of the ThCr2Si2 Structure Type.

Structural instability has a strong influence on the understanding of superconductivity in iron-containing 122 phases. Similar to the 122 iron-based high-temperature superconductors, the intermetallic compound BaNi2Ge2 undergoes an orthorhombic-to-tetragonal structural phase transition. The compound was prepared by arc-melting mixtures of the elements under an argon atmosphere. Single crystals were obtained by a special heat treatment in a welded tantalum ampule. The crystal structure of the compound was investigated by powder and single-crystal X-ray diffraction. Differential thermal analysis of BaNi2Ge2 showed a reversible phase transition at ca. 480 °C. In situ temperature-dependent synchrotron powder X-ray diffraction studies revealed that below 480 °C the crystal structure of BaNi2Ge2 is orthorhombic [own structure type, space group Pnma, a = 8.3852(4) Å, b = 11.3174(8) Å, and c = 4.2902(9) Å at 30 °C] and the high-temperature phase above 510 °C belongs to the tetragonal ThCr2Si2-type structure [space group I4/mmm, a = 4.2664(1) Å, and c = 11.2537(3) Å at 510 °C]. The reversible first-order low-temperature ↔ high-temperature phase transition around 480 °C is associated with distortion of the [Ni2Ge2] layer of low-temperature modification. The anisotropy of thermal expansion of the unit cell in BaNi2Ge2 was analyzed. The crystal chemistry and chemical bonding are discussed in terms of linear muffin-tin orbital band structure calculations and a topological analysis using the electron localization function. In related compounds, the level of distortion of the uncollapsed tetragonal ThCr2Si2-type structure depends on the valence electron count (VEC).

Reply to “Comment on ‘Correlation and relativistic effects in U metal and U-Zr alloy: Validation ofab initioapproaches’ ”

In the Comment by S\oderlind et al. [Phys. Rev. B 90, 157101 (2014)], the authors argue that (1) density functional theory (DFT), especially with all-electron methods, already models U metal and U-Zr alloy accurately; and (2) $\mathrm{DFT}+U$ results calculated at ${U}_{\mathrm{eff}}=1.24$ for volume, enthalpy, and magnetic moments that they select from our study [Phys. Rev. B 88, 235128 (2013)] suggest adding the Hubbard $U$ potential in $\mathrm{DFT}+U$ reduces accuracy compared to DFT. With respect to argument (1) by S\oderlind et al., we argue that previously neglected and very recent experimental data suggest that DFT in S\oderlind's full-potential linear muffin-tin orbital calculations [Phys. Rev. B 66, 085113 (2002)] still models the bulk modulus and elastic constants of \ensuremath{\alpha}U with errors considerably larger than other related elements, e.g., most transition metals. In addition, we demonstrate that the assertion by S\oderlind et al. that our DFT results are not satisfactory because deficiency exists in our projector augmented wave calculation is unfounded. With respect to argument (2) by S\oderlind et al., we argue that they have inappropriately focused on just one phase [the bcc phase \ensuremath{\gamma}(U,Zr)], neglecting the other phases which represent the majority of our evidence; made overgeneralizations based on results at only one ${U}_{\mathrm{eff}}$ value of 1.24 eV; and supported their argument with inaccurate assertions that $\mathrm{DFT}+U$ predicts for \ensuremath{\gamma}(U,Zr) an unprecedentedly large positive volume of mixing and an enthalpy of mixing that is inconsistent with the experimental miscibility gap. We therefore hold to our original conclusion that the accuracy of DFT for modeling U and U-Zr has room for improvement and $\mathrm{DFT}+U$ is a good candidate.

Response to letter “Electron correlation and relativity of the 5f electrons in the U[sbnd]Zr alloy system”

In the Letter [Söderlind et al., J. Nucl. Mater. 444, 356 (2014)], Söderlind et al. state their interpretation that 1) we view electron correlation to be strong and including spin-orbit coupling (SOC) to be necessary for U metal and UZr alloy in our article [Xiong et al., J. Nucl. Mater. 443, 331 (2013)]. Further, they argue that 2) density functional theory (DFT) without adding the Hubbard U potential, especially when solved using all electron methods, already models U and UZr accurately, and 3) adding the Hubbard U potential to DFT in DFT + U models U and UZr worse than DFT according to volume, bulk modulus, and magnetic moments predicted from their calculations of the γU phase of elemental U metal. With respect to Söderlind et al.’s interpretation 1), we clarify that our opinions are that U and UZr are not strongly, but weakly to moderately correlated and that including SOC is beneficial but not necessary for modeling most ground state properties of U and UZr. With respect to Söderlind et al.’s argument 2) we demonstrate that previously neglected and very recent experimental data suggest that DFT in Söderlind's full-potential linear muffin-tin orbital calculations [Söderlind, Phys. Rev. B 66, 085113 (2002)] in fact models the bulk modulus and elastic constants of αU with errors considerably larger than other related elements, e.g., most transition metals. With respect to Söderlind et al.’s argument 3) we argue that they have inappropriately focused on just one phase (the BCC γU phase of U metal), neglecting the other phases which represent the majority of our evidence, and made overgeneralizations based on results at only one Ueff value of 2 eV. We therefore maintain our original conclusion that the accuracy of DFT for modeling U and UZr has room for improvement and DFT + U can be of value for this purpose on at least some ground state properties.

Structural, electronic and magnetic properties of Cd1–xTMxS (TM=Co and V) by ab-initio calculations

The structural, electronic and ferromagnetic properties of Cd1−xTMxS (TM=Co and V) compounds at x=0.25, 0.50 and 0.75 in zinc blende (B3) phase, have been investigated using all-electron full-potential linear muffin tin orbital (FP-LMTO) calculations within the frame work of the density functional theory and the generalized gradient approximation. The electronic properties exhibit half-metallic behavior at x=0.25, 0.50, and 0.75 for Cd1–xVxS and x=0.25 and 0.50 for Cd1−xCoxS, while Cd1−xCoxS with x=0.75 is nearly half-metallic. The calculated magnetic moment per substituted transition metal (TM) atom for half-metallic compounds is found to be 3µB, whereas that of a nearly half-metallic compound is 2.29µB. The analysis of band structure and density of states shows that the TM-3d states play a key role in generating spin-polarization and magnetic moment in these compounds. Furthermore, we establish that the p–d hybridization reduces the local magnetic moment of Co and enhances that of V from their free space charge value of 3µB and creates small local magnetic moments on nonmagnetic Cd and S sites. The exchange constant N0α and N0β have been calculated to validate the effects resulting from exchange splitting process.

Ce11Ge3.73(2)In6.27: Solid-state synthesis, crystal structure and site-preference

A novel intermetallic compound of Ce11Ge3.73(2)In6.27 has been synthesized through the high-temperature solid-state reaction using Nb-ampoules. A batch of well grown block-/short bar-shaped single-crystals has been obtained, and the crystal structure of the title compound has been characterized by single-crystal X-ray diffraction analyses. Ce11Ge3.73(2)In6.27 adopts the Ho11Ge10-type structure belonging to the tetragonal space group I4/mmm (Z=4, Pearson symbol tI84) with nine crystallographically unique atomic positions in the asymmetric unit. The lattice parameters are a=12.0163(1)Å and c=16.5396(2)Å. The overall crystal structure can simply be depicted as an assembly of three different types of co-facial cationic polyhedra centered by anions, which is further enclosed by the three-dimensional (3-D) cage-like anionic framework. The extra amount of In is observed in one of three isolated anionic sites resulting in introducing the Ge/In-mixed site at the Wyckoff 4e site. This unique site-preference of In substitution for Ge at the 4e site has been enlightened via the atomic size-aspect which was fully supported and rationalized by the site- and bond-energies analyses using tight-binding linear muffin-tin orbital (TB-LMTO) calculations. Energy-dispersive X-ray spectroscopy (EDS), density of states (DOS), crystal orbital Hamilton population (COHP), and electron localization function (ELF) analyses for the title compound are also presented. Magnetic susceptibility measurement proves that an antiferromagnetic ordering of Ce atoms at a low temperature with a paramagnetic Curie temperature of −23.2K.

New insights into the application of the valence rules in Zintl phases—Crystal and electronic structures of Ba7Ga4P9, Ba7Ga4As9, Ba7Al4Sb9, Ba6CaAl4Sb9, and Ba6CaGa4Sb9

Crystals of three new ternary pnictides—Ba7Al4Sb9, Ba7Ga4P9, and Ba7Ga4As9 have been prepared by reactions of the respective elements in molten Al or Pb fluxes. Single-crystal X-ray diffraction studies reveal that the three phases are isotypic, crystallizing in the orthorhombic Ba7Ga4Sb9-type structure (space group Pmmn, Pearson symbol oP40, Z=2), for which only the prototype is known. The structure is based on TrPn4 tetrahedra (Tr=Al, Ga; Pn=P, As, Sb), connected in an intricate scheme into 1D-ribbons. Long interchain Pn–Pn bonds (dP–P>3.0Å; dAs–As>3.1Å; dSb–Sb>3.3Å) account for the realization of 2D-layers, separated by Ba2+ cations. Applying the classic valance rules to rationalize the bonding apparently fails, and Ba7Ga4Sb9 has long been known as a metallic Zintl phase. Earlier theoretical calculations, both empirical and ab-initio, suggest that the possible metallic properties originate from filled anti-bonding Pn–Pn states, and the special roles of the “cations” in this crystal structure. To experimentally probe this hypothesis, we sought to synthesize the ordered quaternary phases Ba6CaTr4Sb9 (Tr=Al, Ga). Single-crystal X-ray diffraction work confirms Ba6.145(3)Ca0.855Al4Sb9 and Ba6.235(3)Ca0.765Ga4Sb9, with Ca atoms preferably substituting Ba on one of the three available sites. The nuances of the five crystal structures are discussed, and the chemical bonding in Ba7Ga4As9 is interrogated by tight-binding linear muffin-tin orbital calculations.

Crystal structure, chemical bonding and magnetism studies for three quinary polar intermetallic compounds in the (Eu(1-x)Ca(x))9In8(Ge(1-y)Sn(y))8 (x = 0.66, y = 0.03) and the (Eu(1-x)Ca(x))3In(Ge(3-y)Sn(1+y)) (x = 0.66, 0.68; y = 0.13, 0.27) phases.

Three quinary polar intermetallic compounds in the (Eu1−xCax)9In8(Ge1−ySny)8 (x = 0.66, y = 0.03) and the (Eu1−xCax)3In(Ge3-ySn1+y) (x = 0.66, 0.68; y = 0.13, 0.27) phases have been synthesized using the molten In-metal flux method, and the crystal structures are characterized by powder and single-crystal X-ray diffractions. Two orthorhombic structural types can be viewed as an assembly of polyanionic frameworks consisting of the In(Ge/Sn)4 tetrahedral chains, the bridging Ge2 dimers, either the annulene-like “12-membered rings” for the (Eu1−xCax)9In8(Ge1−ySny)8 series or the cis-trans Ge/Sn-chains for the (Eu1−xCax)3In(Ge3−ySn1+y) series, and several Eu/Ca-mixed cations. The most noticeable difference between two structural types is the amount and the location of the Sn-substitution for Ge: only a partial substitution (11%) occurs at the In(Ge/Sn)4 tetrahedron in the (Eu1−xCax)9In8(Ge1−ySny)8 series, whereas both a complete and a partial substitution (up to 27%) are observed, respectively, at the cis-trans Ge/Sn-chain and at the In(Ge/Sn)4 tetrahedron in the (Eu1−xCax)3In(Ge3−ySn1+y) series. A series of tight-binding linear muffin-tin orbital calculations is conducted to understand overall electronic structures and chemical bonding among components. Magnetic susceptibility measurement indicates a ferromagnetic ordering of Eu atoms below 5 K for Eu1.02(1)Ca1.98InGe2.87(1)Sn1.13.

Single-crystal growth and size control of three novel polar intermetallics: Eu2.94(2)Ca6.06In8Ge8, Eu3.13(2)Ca5.87In8Ge8, and Sr3.23(3)Ca5.77In8Ge8 with crystal structure, chemical bonding, and magnetism studies.

Three new quaternary polar intermetallic compounds of Eu2.94(2)Ca6.06In8Ge8, Eu3.13(2)Ca5.87In8Ge8, and Sr3.23(3)Ca5.77In8Ge8 have been synthesized by a metal-flux method using molten indium metal as a reactive flux, and the novel isotypic crystal structures have been characterized by both powder and single-crystal X-ray diffractions. All compounds crystallize in the orthorhombic space group Pmmn (Z = 2, Pearson symbol oP50) with 14 crystallographically unique atomic positions in the asymmetric unit. The lattice parameters are refined as follows: a = 36.928(2) Å, b = 4.511(1) Å, and c = 7.506(1) Å for Eu2.94(2)Ca6.06In8Ge8; a = 37.171(19) Å, b = 4.531(2) Å, and c = 7.560(4) Å for Eu3.13(2)Ca5.87In8Ge8; and a = 37.350(2) Å, b = 4.550(3) Å, and c = 7.593(4) Å for Sr3.23(3)Ca5.77In8Ge8. In particular, single crystals of two Eu-containing compounds are obtained as bundles of bar/needle-shaped crystals, and the thicknesses of those crystals can be controlled in the range between ca. 300 μm and ca. <10 μm by adjusting several reaction conditions, including the reaction cooling rate and the centrifugation temperature. The overall crystal structure is illustrated as an assembly of (1) the three-dimensional anionic framework, which is formed by the chains of edge-sharing InGe4 tetrahedra and the annulene-like "12-membered anionic rings" connected via Ge2 dimers, and (2) the cationic mixed sites embedded in the space between the anionic frameworks. Theoretical investigations based on tight-binding linear muffin-tin orbital (TB-LMTO) calculations provide a comprehesive understanding of the overall electronic structure and chemical bonding observed among anionic components and between anions and cations. Electron localization function (ELF) and electron density map present chemical bond strengths and polarization within the anionic framework. Magnetic susceptibility measurement proves an antiferromagnetic (AFM) ordering of Eu atoms below 4 K with a reduced effective magnetic moment of 7.12 μB for the Eu atom.

Electronic structure, chemical bonding and magnetism of the metal-rich borides MRh6B3 (M = Cr, Mn, Fe, Co, Ni) with Th7Fe3-type structure: A density functional theory study

The electronic structures, magnetic properties and chemical bonding of MRh6B3 (M = Cr, Mn, Fe, Co, Ni) were analyzed theoretically by first-principles density functional theory. All functionals used correctly reproduced the magnetic state of all experimentally characterized phases MRh6B3 (M = Cr, Fe, Co, Ni). In addition, ferromagnetic ordering is predicted in MnRh6B3, which is yet to be synthesized and characterized, with a magnetic saturation moment predicted to lie between 3.55 μB (LDA) and 4.07 μB (GGA). Linear muffin tin orbital (LMTO) calculations were applied to study the chemical bonding and magnetism in all phases. These calculations show that the Rh–B contacts are responsible for the structural stability, while the Rh–M interactions influence the magnetic behavior, whereas the M–B interactions regulate the variation of the unit cell volume in the series. The non-vanishing DOS values at all Fermi levels suggest metallic character for all phases as expected for these intermetallic compounds.

Synthesis, Crystal Chemistry, and Magnetic Properties of RE7Li8Ge10 and RE11Li12Ge16 (RE = La–Nd, Sm): New Members of the [REGe2]n[RELi2Ge]m Homologous Series

Eight new rare-earth metal-lithium-germanides belonging to the [REGe(2)](n)[RELi(2)Ge](m) homologous series have been synthesized and structurally characterized by single-crystal X-ray diffraction. The structures of the title compounds can be rationalized as linear intergrowths of imaginary RELi(2)Ge (MgAl(2)Cu structure type) and REGe(2) (AlB(2) structure type) slabs. The compounds with general formula RE(7)Li(8)Ge(10) (RE = La-Nd, Sm), i.e., [REGe(2)](3)[RELi(2)Ge](4), crystallize in the orthorhombic space group Cmmm (No. 65) with a new structure type. Similarly, the compounds with general formula RE(11)Li(12)Ge(16) (RE = Ce-Nd), i.e., [REGe(2)](5)[RELi(2)Ge](6), crystallize in the orthorhombic space group Immm (No. 71) also with its own structure type. Temperature-dependent DC magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime and hint at complex magnetic ordering at low temperatures. The measured effective moments are consistent with RE(3+) ground states in all cases. The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB-LMTO) electronic structure calculations.

CdGeN&lt;sub&gt;2&lt;/sub&gt; and ZnGe&lt;sub&gt;0.5&lt;/sub&gt;Sn&lt;sub&gt;0.5&lt;/sub&gt;N&lt;sub&gt;2&lt;/sub&gt;: Two New Nitride Semiconductors with Band Gaps in the Blue-Green

First-principles calculations are presented for CdGeN2 and ZnGe0.5Sn0.5N2 compounds with the orthorhombic structure derived from wurtzite. Lattice constants and internal parameters are obtained from local density approximation full-potential linearized muffin-tin orbital calculations and the quasiparticle self-consistent GW method is used to calculate the band structures. Corrections for zero-point motion and exciton binding energy are included. Both approaches lead to gaps in the blue-green region.

Ferrimagnetism in Fe-rich NbFe2

We report a study of the spin moment in single crystal Nb${}_{(1\ensuremath{-}y)}$Fe${}_{(2+y)}$ with $y=0.015$ using spin-dependent Compton scattering in conjunction with ab initio electronic structure calculations. From the experiment, we find that the total spin moment is $0.245\ifmmode\pm\else\textpm\fi{}0.004{\ensuremath{\mu}}_{B}$. Comparison of the measured spin density with theoretical results from linearized muffin-tin orbital calculations determines there to be a ferrimagnetic arrangement of Fe moments, with the 2$a$ Fe site aligned antiparallel to the bulk moment. There is a small moment on the Nb site, also antiparallel to the net moment. The orbital moment has been determined to be $0.02\ifmmode\pm\else\textpm\fi{}0.02{\ensuremath{\mu}}_{B}$.