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Introduction Les etudes dans l’ASE ont demontre de facon recurrente l’efficacite du MEPO sur la reduction des exacerbations. Dans ces etudes, environ la moitie des patients ASE etaient allergiques et un tiers etaient eligibles a un traitement par OMA. Il n’existe pas de donnees a ce jour evaluant l’effet du MEPO sur la reduction des exacerbations chez des patients ASE deja traites par OMA. Methodes Il s’agit d’une etude complementaire de l’etude MENSA (Ortega et al., NEJM 2014) qui a inclus 576 patients ≥ 12 ans recevant des corticoides inhales a fortes doses plus un autre traitement de fond, avec des antecedents d’exacerbations frequentes et un seuil d’eosinophiles predefini. L’OMA n’etait pas autorise durant l’etude. Les taux d’IgE specifiques et totales avant OMA et les raisons de son arret ont ete recueillis. Une analyse post-hoc des taux d’exacerbations a ete menee a partir de modeles binomiaux negatifs separes pour chaque sous-groupe. Resultats Soixante-quinze patients (13 %) avaient deja recu OMA pendant une duree mediane de 12 mois. Trente-sept patients (50 %) avaient ete traites par OMA toutes les 2 semaines. L’absence d’efficacite etait la raison de l’arret d’OMA chez la majorite des patients (75 %). Les donnees demographiques a l’inclusion des patients deja traites par OMA etaient comparables a celles des patients n’en ayant pas recu. Le MEPO a permis une reduction significative et similaire du taux d’exacerbations entre les patients deja traites par OMA (rapport de frequence : 0,43 ; IC95 % : 0,21 ; 0,88) et ceux non traites anterieurement (rapport de frequence : 0,53 ; IC95 % : 0,40 ; 0,69). Conclusion Chez les patients avec un ASE, le MEPO a permis de reduire significativement les exacerbations que les patients aient ou non deja recu OMA (etude financee par GlaxoSmithKline). Cet abstract a deja ete presente lors du congres annuel de l’AAAAI 2015 : Albers FC, et al. JACI 2015;135:AB383 (L7) et est reproduit avec l’autorisation d’Elsevier.

A program is presented which implements the layer Koringer-Kohn-Rostoker theory for the electronic structure of both bulk systems and those characterised by two-dimensional periodicity. The one-electron Green function is obtained by recursively assembling the layers of the system, permitting the study of interface regions embedded in otherwise perfect host materials. The program enables the calculation of self-consistent charge densities and localised states.

The electronic structure of the (001) face of ordered Cu3Au was studied using synchrotron radiation at BESSY, in the photon energy range 22–80 eV. The Cu 3d-derived bands in Cu3Au look like the foldedd-bands of fcc Cu metal. Three Au 5d-derived bands were observed at 5.0, 6.1 and 7.0 eV below the Fermi level, which showed no dispersion with change in photon energy. The Cu 3d- and the Au 5d-derived bands are found to be separated in energy. We have calculated self-consistent energy bands along the (001) direction using the fully relativistic LMTO method. Comparison of these bands with those experimentally determined shows good agreement. From the calculated bands along Γ−X the direction dependent densities of states were determined, which give a consistent account for the non-dispersive Au-bands.

A series of simulations has been performed on grain boundaries in Ni and Ni3Al with and without boron doping using embedded atom-style potentials. A new procedure of obtaining “reference” data for boron related properties from electronic band structure calculations has been employed. Good agreement with existing experimental structural and energetic determinations was obtained. Boron is found to segregate more strongly to grain boundaries than to free surfaces. Adding boron to grain boundaries in Ni and Ni3Al increases their cohesive strength and the work required to pull apart the boundary. This effect is much more dramatic for Ni-rich boundaries than for stoichiometric or Al-rich boundaries. In some Ni-rich cases, adding boron increases the cohesive strength of the boundary to such an extent that the boundaries become stronger than the bulk. Bulk Ni3Al samples that are Ni-rich produce Ni-rich grain boundaries. The best cohesive properties of Ni3Al grain boundaries are obtained when the boundary is Ni saturated and also with boron present. Boron and nickel are found to cosegregate to the grain boundaries.

Aluminum sandwich foils can be compressed to more than twice the normal density by the use of shock waves generated by laser beams. We present calculations of the K-edge absorption structure of two fold compressed aluminum, and compare the results with experimental data. The atomic potential is calculated using a spherical band-structure model with Fermi-Dirac statistics for the electrons. The structure above the K-edge is calculated according to the Müller-Shaich formula for the propagating photo-electron. The mean free path of the electron is taken into account through a complex exchange correlation potential. An appropriate Debye-Waller factor is used to represent the effect of the relatively high temperature encountered in these experiments.

Drawing on John Berger's analytical distinction between the “private” and “public” photograph, this paper shows how the differing uses to which postcard pictures were put, and how the differing audiences which viewed them influenced the stereotypic as well as authentic ways in which Great Basin Indians were represented on the postcard from 1900 to 1920. In so doing, it offers a critical perspective for understanding the role that photography has played in fostering faithful as well as distorted images of the American Indian.

By combining the local density approximation (LDA) with dynamical mean field theory (DMFT), we report a systematic analysis of the spectral properties of $\ensuremath{\delta}$-plutonium with varying $5f$ occupancy. The LDA Hamiltonian is extracted from a tight-binding fit to full-potential linearized augmented plane-wave calculations. The DMFT equations are solved by the exact quantum Monte Carlo (QMC) method and by the Hubbard-I approximation. We demonstrate strong sensitivity of the spectral properties to the $5f$ occupancy, which suggests using this occupancy as a fitting parameter in addition to the Hubbard $U$. By comparing with photoemission data, we conclude that the ``open shell'' $5{f}^{5}$ configuration gives the best agreement, resolving the controversy over $5f$ ``open shell'' versus ``close shell'' atomic configurations in $\ensuremath{\delta}\text{\ensuremath{-}}\mathrm{Pu}$.

A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with the voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin-density approximation, we calculate the spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of the applied bias voltage. We find a change in sign of the spin polarization of tunneling electrons with bias voltage due to the interface minority-spin resonance. This result explains recent experimental data on spin injection in Fe/GaAs contacts and on tunneling magnetoresistance in Fe/GaAs/Fe magnetic tunnel junctions.

Continuing the photoemission study begun with the work of Opeil et al. [Phys. Rev. B \textbf{73}, 165109 (2006)], in this paper we report results of an angle-resolved photoemission spectroscopy (ARPES) study performed on a high-quality single-crystal $\alpha$-uranium at 173 K. The absence of surface-reconstruction effects is verified using X-ray Laue and low-energy electron diffraction (LEED) patterns. We compare the ARPES intensity map with first-principles band structure calculations using a generalized gradient approximation (GGA) and we find good correlations with the calculated dispersion of the electronic bands.

Background: Despite advances in colorectal cancer (CRC) screening, early detection, and treatment, CRC remains the 2nd most common cancer cause of death in the U.S.. Obesity is increasing in incidence in the U.S., and has been implicated in colorectal adenoma (CRA) risk, risk of CRA recurrence, and risk of CRC. Obese patients with history of CRA are a high-risk group that may benefit from novel CRC prevention strategies. There is early evidence for reduced cancer mortality among metformin users. The signaling pathway activated by metformin (LKB1/AMPK/mTOR) is implicated in tumor suppression in ApcMin/+ mice, as evidenced by metformin-induced reduction in polyp burden, increased ratio of pAMPK/AMPk, decreased ratio of pmTOR/mTOR, and decreased ratio of pS6Ser235/S6Ser235 in polyp specimens. We hypothesized that metformin would affect colorectal tissue S6Ser235 similarly in humans, targeting obese patients with recent history of CRAs as a high-risk group. Methods: A phase IIa clinical biomarker trial was conducted across 3 clinical sites via the NCI-funded Southern California Chemoprevention Program. Eligible participants included non-diabetic, obese patients (BMI >30) with history of colorectal adenoma within the past 3 years, age ≥ 35 years and ≤ 80 years. All patients received an upward titration of metformin over 3 weeks to 1000mg po bid, which was continued until the end-of-study (EOS) at 12 weeks. Rectal mucosa biopsies were obtained at baseline (BL) and at time of EOS endoscopy. Tissue S6Ser235 immunostaining was analyzed in a blinded fashion by the study pathologist using Histo Score (HScore) analysis. A paired t-test was used to examine the effect of metformin on activated S6serine235 (i.e., the ratio of pS6serine235/ S6serine235). Results: 45 patients were consented to achieve 32 eligible subjects. 4 subjects were removed from study due to Adverse Events (1 SAE, unrelated). In order of frequency, the most common AEs were diarrhea, cramping, flatulence, nausea, stomach pain; 80% of participants had Grade 1 AE, 27% had grade 2 AE. Mean (SD) weight and body mass index at BL were 105.2 (17.42) kg and 34.9 (5.57) respectively. Weight did not significantly differ over the course of the study. Glucose levels at EOS did not significantly differ from BL. Vitamin B12 levels were significantly reduced at EOS vs. BL (-46.7 pg/mL, 95% CI -73.2 to -20.2). Comparing EOS to BL tissue S6Ser235 by IHC HScore analysis, no significant differences were observed. Mean (SD) Hscore at BL was 1.1 (0.57) and 1.1 (0.51) at EOS. Median HScore change was 0.032 (p=0.77). Conclusions: Among obese CRA patients, 12 weeks of oral metformin 1000mg twice daily does not reduce pS6 levels in the rectal mucosa. Other potential mechanisms of action have not yet been analyzed. Data from this clinical trial indicate that metformin can be used safely in a non-diabetic population. Further research is needed to determine what effects, if any, metformin has on the target tissue of origin (colorectum) relevant to colorectal carcinogenesis if metformin is to be pursued as a CRC chemopreventive agent. Citation Format: Jason A. Zell, Christine E. McLaren, Timothy R. Morgan, Michael J. Lawson, Sherif Rezk, Gregory C. Albers, Wen-Pin Chen, Joseph C. Carmichael, Luz Rodriguez, Eva Szabo, Leslie Ford, Michael Pollak, Frank L. Meyskens. A Phase IIa trial of metformin for colorectal cancer risk reduction among patients with a history of colorectal adenomas and elevated body mass index. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A21.

We have calculated the phonons and elastic constants of zirconium in the hexagonal-close-packed (hcp) crystal structure using the Naval Research Laboratory (NRL) empirical tight-binding (TB) approach; the tight-binding parameters are obtained by fitting to ab initio density-functional theory--generalized gradient approximation energy bands and total energies for many different structures and volumes. We address difficulties involved with the fitting procedure and give results for elastic constants, force constants, quasiharmonic phonons, and specific heat. Because the predicted TB lattice constants at the zero-temperature energy minimum are slightly different from those experimentally observed at room temperature, our TB model has an anisotropic stress at the experimental lattice constants. We correct for these stresses in our calculations of the elastic constants and sound speeds. Such techniques are also useful for calculating such properties for arbitrary $c∕a$. Our phonon calculations were done by the direct-force method in real space using calculated force constants; these fall off quite slowly with distance, which causes problems with the calculated phonon spectrum due to the slow convergence with increasing supercell size. This long-range behavior could play a large role in determining the unusually anharmonic and anomalous physical properties of Zr. We show that similar, although less severe, problems should arise for other metals. These considerations suggest that the direct-force method for calculating phonons may be problematic for many metals.

Valence-band ultraviolet photoemission spectroscopy (UPS) at 173 K and 6p core-level x-ray photoemission spectroscopy (XPS) at room temperature were performed on a high quality uranium single crystal. Significant agreement is found with first-principles electronic band-structure calculations, using a generalized gradient approximation (GGA). In addition, using low energy electron diffraction (LEED) for the (001) surface, we find a well-ordered orthorhombic crystallographic structure representative of the bulk material.

For a previously published study of the titanium hcp (alpha) to omega (omega) transformation, a tight-binding model was developed for titanium that accurately reproduces the structural energies and electron eigenvalues from all-electron density-functional calculations. We use a fitting method that matches the correctly symmetrized wavefuctions of the tight-binding model to those of the density-functional calculations at high symmetry points. The structural energies, elastic constants, phonon spectra, and point-defect energies predicted by our tight-binding model agree with density-functional calculations and experiment. In addition, a modification to the functional form is implemented to overcome the "collapse problem" of tight-binding, necessary for phase transformation studies and molecular dynamics simulations. The accuracy, transferability and efficiency of the model makes it particularly well suited to understanding structural transformations in titanium., 9 pages, 8 figures, 5 tables

Martensitic phase transitions appear in a diverse range of natural and engineering material systems. Examination of the energetics and kinetics of the transformation requires an understanding of the atomic mechanism for the transformation. A systematic pathway generation and sorting algorithm is presented and applied to the problem of the titanium $\ensuremath{\alpha}$ to $\ensuremath{\omega}$ transformation under pressure. The transformation pathways are separated into strain and shuffle components. All pathways are constructed within energetically motivated strain and shuffle constraints, and efficiently sorted by their energy barriers. The geometry and symmetry details of the seven lowest energy barrier pathways are given. The lack of a single simple geometric criterion for determining the lowest energy pathway shows the necessity of atomistic studies for pathway determination. The general algorithm can determine the pathway for any martensitic transformation.

We introduce a framework for modeling elastic properties of shape memory alloy polycrystals by coupling orientational degrees of freedom with elastic strains. Our method allows us to span the length scales from single crystal to that appropriate to obtain polycrystal properties. The single crystal free energy coefficients can be determined from microscopic calculations (such as electronic structure and molecular dynamics) and/or available experimental structural, phonon and thermodynamic data. We simulate the microstructure and determine the stress-strain response of the polycrystal and compare it with that of a single crystal. For FePd parameters we find that the recoverable strain for a polycrystal is ~ 40% of that for a single crystal. The polycrystal information can, in principle, serve as input to the engineering scale of calculation, where the finite element method is appropriate.

We propose a new pseudophase crystal structure, based on an orthorhombic distortion of the diamond structure, for the ground-state $\ensuremath{\alpha}$ phase of plutonium. Electronic-structure calculations in the generalized-gradient approximation give approximately the same total energy for the two structures. Interestingly, our new pseudophase structure is the same as the $\ensuremath{\gamma}$-Pu structure except with very different $b/a$ and $c/a$ ratios. We show how the contraction relative to the $\ensuremath{\gamma}$ phase, principally in the $z$ direction, leads to an $\ensuremath{\alpha}$-like structure in the $[0,1,1]$ plane and reproduces the short range bonds of the $\ensuremath{\alpha}$ phase. This is an important link between two complex structures of Pu and opens new possibilities for exploring the very rich phase diagram of Pu through theoretical calculations.

Impurities control phase stability and phase transformations in natural and man-made materials, from shape-memory alloys to steel to planetary cores. Experiments and empirical databases are still central to tuning the impurity effects. What is missing is a broad theoretical underpinning. Consider, for example, the titanium martensitic transformations: diffusionless structural transformations proceeding near the speed of sound. Pure titanium transforms from ductile alpha to brittle omega at 9 GPa, creating serious technological problems for beta-stabilized titanium alloys. Impurities in the titanium alloys A-70 and Ti-6Al-4V (wt%) suppress the transformation up to at least 35 GPa, increasing their technological utility as lightweight materials in aerospace applications. These and other empirical discoveries in technological materials call for broad theoretical understanding. Impurities pose two theoretical challenges: the effect on the relative phase stability, and the energy barrier of the transformation. Ab initio methods calculate both changes due to impurities. We show that interstitial oxygen, nitrogen and carbon retard the transformation whereas substitutional aluminium and vanadium influence the transformation by changing the d-electron concentration. The resulting microscopic picture explains the suppression of the transformation in commercial A-70 and Ti-6Al-4V alloys. In general, the effect of impurities on relative energies and energy barriers is central to understanding structural phase transformations.

EXAFS measurements of vanadium shocked to ~0.4 Mbar yield the compression and temperature in good agreement with hydrodynamic simulations and shock-speed measurements. In laser-shocked titanium at the same pressure, the EXAFS spectrum indicates the ?-Ti to ?-Ti crystal-phase transformation, known to occur below ~0.1 Mbar for slower shock waves.

We propose using an equation-of-motion approach as an impurity solver for dynamical mean field theory. As an illustration of this technique, we consider a finite-$U$ Hubbard model defined on the Bethe lattice with infinite connectivity at arbitrary filling. Depending on the filling, the spectra that is obtained exhibits a quasiparticle peak, and lower and upper Hubbard bands as typical features of strongly correlated materials. The results are also compared and in good agreement with exact diagonalization. We also find a different picture of the spectral weight transfer than the iterative perturbation theory., Comment: 5 pages, 2 figures

Extended x-ray absorption fine structure (EXAFS), using a laser-imploded target as a source, can yield the properties of laser-shocked metals on a nanosecond time scale. EXAFS measurements of vanadium shocked to $\ensuremath{\sim}0.4\text{ }\mathrm{M}\mathrm{b}\mathrm{a}\mathrm{r}$ yield the compression and temperature in good agreement with hydrodynamic simulations and shock-speed measurements. In laser-shocked titanium at the same pressure, the EXAPS modulation damping is much higher than is warranted by the predicted temperature increase. This is shown to be due to the $\ensuremath{\alpha}\mathrm{\text{\ensuremath{-}}}\mathrm{T}\mathrm{i}$ to $\ensuremath{\omega}\mathrm{\text{\ensuremath{-}}}\mathrm{T}\mathrm{i}$ crystal phase transformation, known to occur below $\ensuremath{\sim}0.1\text{ }\mathrm{M}\mathrm{b}\mathrm{a}\mathrm{r}$ for slower shock waves.

Unscreened Hartree-Fock approximation (HFA) calculations for metallic Fe, Co, Ni, and Cu are presented, by using a quantum-chemical approach. We believe that these are the first HFA results to have been done for crystalline 3d transition metals. Our approach uses a linearized muffin-tin orbital calculation to determine Bloch functions for the Hartree one-particle Hamiltonian, and from these obtains maximally localized Wannier functions, using a method proposed by Marzari and Vanderbilt. Within this Wannier basis all relevant one-particle and two-particle Coulomb matrix elements are calculated. The resulting second-quantized multi-band Hamiltonian with ab-initio parameters is studied within the simplest many-body approximation, namely the unscreened, self-consistent HFA, which takes into account exact exchange and is free of self-interactions. Although the d-bands sit considerably lower within HFA than within the local (spin) density approximation L(S)DA, the exchange splitting and magnetic moments for ferromagnetic Fe, Co, and Ni are only slightly larger in HFA than what is obtained either experimentally or within LSDA. The HFA total energies are lower than the corresponding LSDA calculations. We believe that this same approach can be easily extended to include more sophisticated ab-initio many-body treatments of the electronic structure of solids., 11 papes, 7 figures, 5 tables

We propose a new direct mechanism for the pressure driven $\ensuremath{\alpha}\ensuremath{\rightarrow}\ensuremath{\omega}$ martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.

We have used a tight-binding model that is fit to first-principles electronic-structure calculations for titanium to calculate quasiharmonic phonons and the Gibbs free energy of the hexagonal-close-packed (hcp) and omega (ω) crystal structures. The hcp phonon dispersion agrees with experiment; the ω phonon dispersion has yet to be measured. The model predicts that the true zero-temperature ground state is the ω structure and that it is the entropy from the thermal population of phonon states which stabilizes the hcp structure at room temperature. We present a completely theoretical prediction of the temperature and pressure dependence of the hcp-ω phase transformation and show that it is in good agreement with experiment. The quasiharmonic approximation fails to adequately treat the bcc phase because the calculated phonons of this structure are not all stable.

We propose a new pseudophase crystal structure, based on an orthorhombic distortion of the diamond structure, for the ground-state alpha phase of plutonium. Electronic-structure calculations in the generalized-gradient approximation give approximately the same total energy for the two structures. Interestingly, our new pseudophase structure is the same as the gamma-Pu structure except with very different b/a and c/a ratios. We show how the contraction relative to the gamma phase, principally in the z direction, leads to an alpha-like structure in the [0,1,1] plane and reproduces the short range bonds of the alpha phase. This is an important link between two complex structures of Pu and opens new possibilities for exploring the very rich phase diagram of Pu through theoretical calculations.

In a recent paper [Phys. Rev. B $63,$ 224115 (2001)], we proposed two equations of state based upon microscopic insight into the cohesion of a solid: the stabilized jellium equation of state (SJEOS) and its augmented version (ASJEOS). In this Reply, we address the issues raised by Holzapfel in his Comment on that paper. We show that, according to the number of independent fitting parameters used, our ASJEOS is comparable with Holzapfel's third-order adapted polynomial (AP3) and that the ASJEOS performs slightly better than AP3 for the materials (Al, Li, and Mo) and pressure range $(P\ensuremath{\lesssim}15\mathrm{Mbar})$ discussed in our paper. We compare the advantages and the disadvantages of ASJEOS and AP3, and discuss the behavior of the equations of state as they approach the strong-compression and strong-expansion limits.

We propose a new direct mechanism for the pressure driven alpha--omega martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.

We propose a Ginzburg-Landau theory for the elastic properties of shape memory polycrystals. A single crystal elastic free energy for a system that undergoes a square-to-rectangle transformation is generalized to a polycrystal by introducing a crystal orientational field that is determined from a continuum phase field model. The coupled system is used to study domain morphology and mechanical properties of shape memory alloys in different temperature regimes., Comment: To appear in Acta Materialia

We extend a tight-binding total energy method to include f-electrons, and apply it to the study of the structural and elastic properties of a range of elements from Be to U. We find that the tight-binding parameters are as accurate and transferable for f-electron systems as they are for d-electron systems. In both cases we have found it essential to take great care in constraining the fitting procedure by using a block-diagonalization procedure, which we describe in detail., 9 pages, 6 figures

A tight-binding model is fit to first-principles calculations for copper that include structures distorted according to elastic constants and high-symmetry phonon modes. With the resulting model the first-principles-based phonon dispersion and the free energy are calculated in the quasi-harmonic approximation. The resulting thermal expansion, the temperature- and volume-dependence of the elastic constants, the Debye temperature, and the Gruneisen parameter are compared with available experimental data., submitted to Physical Review B

We present the construction of free energy functions for the α and ω phases of Ti. These free energies combine information from ambient pressure, static high pressure, and shock wave measurements as well as first principles total energy calculations. The Hugoniot data are analyzed in terms of this equation of state. The Hugoniot consists of three segments: a metastable α‐phase region, a transition region, and an ω‐phase branch. The extent of the metastability and time resolved wave profiles are discussed in terms of a model in which the transformation rate depends exponentially on the pressure, an assumption which is motivated by static high‐pressure data. This picture is consistent with the observed wave shapes and with the observation that the apparent transformation pressure is dependent on the peak shock pressure.

We model a cubic-to-tetragonal martensitic transition by a Ginzburg-Landau free energy in the symmetric strain tensor. We show in three dimensions (3D) that solving the St. Venant compatibility relations for strain, treated as independent field equations, generates three anisotropic long-range potentials between the two order parameter components. These potentials encode 3D discrete symmetries, express the energetics of lattice integrity, and determine 3D textures. Simulation predictions include twins with temperature-varying orientation, helical twins, competing metastable states, and compatibility-induced elastic frustration. Our approach also applies to improper ferroelastics.

Explicit functions are widely used to interpolate, extrapolate, and differentiate theoretical or experimental data on the equation of state (EOS) of a solid. We present two EOS functions which are theoretically motivated. The simplest realistic model for a simple metal, the stabilized jellium (SJ) or structureless pseudopotential model, is the paradigm for our SJEOS. A simple metal with exponentially overlapped ion cores is the paradigm for an augmented version (ASJEOS) of the SJEOS. For the three solids tested (Al, Li, Mo), the ASJEOS matches all-electron calculations better than prior equations of state. Like most of the prior EOS's, the ASJEOS predicts pressure P as a function of compressed volume $v$ from only a few equilibrium inputs: the volume ${v}_{0},$ the bulk modulus ${B}_{0},$ and its pressure derivative ${B}_{1}.$ Under expansion, the cohesive energy serves as another input. A further advantage of the new equation of state is that these equilibrium properties other than ${v}_{0}$ may be found by linear fitting methods. The SJEOS can be used to correct ${B}_{0}$ and the EOS found from an approximate density functional, if the corresponding error in ${v}_{0}$ is known. We also (a) estimate the typically small contribution of phonon zero-point vibration to the EOS, (b) find that the physical hardness $\mathrm{Bv}$ does not maximize at equilibrium, and (c) show that the ``ideal metal'' of Shore and Rose is the zero-valence limit of stabilized jellium.

We study the bcc-hcp phase transition in Ti and Zr with the use of first-principles calculations. We have determined the complete energy surface from the bcc to hcp structure. The results are used to find an appropriate Landau free energy density for describing this transformation. The proposed Landau free energy density has two relevant order parameters: shear and shuffle. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms ${(TA}_{1}$ N-point phonon) rather than the shear. Therefore, we reduce the two order parameter Landau free energy to an effective one order parameter (shuffle) potential, which is a reasonable approximation. In general, the effective Landau free energy is a triple-well potential. From the phonon dispersion data and the change in entropy at the transition temperature we find the free energy coefficients for Ti and Zr.

We present first-principles calculations of optimally localized Wannier functions for Cu and use these for an ab-initio determination of Hubbard (Coulomb) matrix elements. We use a standard linearized muffin-tin orbital calculation in the atomic-sphere approximation (LMTO-ASA) to calculate Bloch functions, and from these determine maximally localized Wannier functions using a method proposed by Marzari and Vanderbilt. The resulting functions were highly localized, with greater than 89% of the norm of the function within the central site for the occupied Wannier states. Two methods for calculating Coulomb matrix elements from Wannier functions are presented and applied to fcc Cu. For the unscreened on-site Hubbard $U$ for the Cu 3d-bands we have obtained about 25eV. These results are also compared with results obtained from a constrained local-density approximation (LDA) calculation., Comment: 13 pages, 8 figures, 5 tables

We have developed a new method[1] of fitting tight-binding parameterizations based on functional forms developed at the Naval Research Laboratory.[2] We have applied these methods to actinide metals and report our success using them (see below). The fitting procedure uses first-principles local-density-approximation (LDA) linear augmented plane-wave (LAPW) band structure techniques[3] to first calculate an electronic-structure band structure and total energy for fcc, bcc, and simple cubic crystal structures for the actinide of interest. The tight-binding parameterization is then chosen to fit the detailed energy eigenvalues of the bands along symmetry directions, and the symmetry of the parameterization is constrained to agree with the correct symmetry of the LDA band structure at each eigenvalue and k-vector that is fit to. By fitting to a range of different volumes and the three different crystal structures, we find that the resulting parameterization is robust and appears to accurately calculate other crystal structures and properties of interest.

The influence of local-spin-dependent correlation effects on the predicted stable ground-state phase of iron is reexamined with use of general-potential linearized augmented-plane-wave calculations. Differences in the form of the Vosko-Wilk-Nusair (VWN) local-spin-density functional used in previous studies are noted, since in previous studies significant additional approximations were made with respect to those of Vosko, Wilk, and Nusan (Can. J. Phys. 58, 1200 (1980)) and of MacLaren, Clougherty, and Albers (Phys. Rev. B 42, 3205 (1990)). While the results of previous linear muffin-tin orbital calculations using the VWN functional predict a bcc ferromagnetic ground state, the present calculations show that the VWN spin-correlation effects fail to stabilize a bcc ground state. Considerable sensitivity to the form of the spin interpolation is found.

The C15 NbCr2 + V Laves phase ternary system is studied by using a first-principles, self-consistent, full-potential total energy method. Equilibrium lattice parameters, cohesive energies, density of states and formation energies of substitutional defects are calculated. Results of all these calculations show that in the C15 NbCr2 + V compounds, V atoms substitute Cr atoms only.