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    Wyświetlanie 1-14 z 14
    Tytuł:
    Electronic Structure of the Ni$\text{}_{3}$Al and Ni$\text{}_{3}$Ga Alloys
    Autorzy:
    Wosicki, P.
    Jezierski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1887737.pdf
    Data publikacji:
    1991-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    Opis:
    The results of ab-initio calculations of the electronic density of states and band electronic structure of the Ni$\text{}_{3}$Al and Ni$\text{}_{3}$Ga alloys are presented.. The calculations are performed with the use of the linear-muffin-tin-orbital (LMTO) method in the atomic sphere approximation. The Barth-Hedin parametrization of the local density exchange correlation energy is used.
    Źródło:
    Acta Physica Polonica A; 1991, 79, 6; 895-904
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetism in FeRh Alloys
    Autorzy:
    Pugacheva, M.
    Jezierski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1861254.pdf
    Data publikacji:
    1994-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    75.10.Lp
    Opis:
    We study the electronic and magnetic properties of FeRh ordered alloys. The electronic structure is calculated by the tight-binding linear muffin-tin orbital method. We observe the decreasing magnetic moment with increase of the ratio c/a during the structural phase transformation from CsCl to CuAu type structure.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 1; 219-221
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electronic Structure of Pt$\text{}_{1-x}$Mn$\text{}_{x}$ and Pt$\text{}_{1-x}$Cr$\text{}_{x}$ Disordered Alloys
    Autorzy:
    Jezierski, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1924282.pdf
    Data publikacji:
    1992-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    75.10.Lp
    Opis:
    Electronic density of states of disordered fcc Pt$\text{}_{1-x}$Mn$\text{}_{x}$ and Pt$\text{}_{1-x}$Cr$\text{}_{x}$ alloys for 0 < x < 0.35 is calculated by the tight-binding linear muffin-tin orbital (TB LMTO) and the coherent potential approximation (CPA) method. Using the Stoner model it was found that the disordered Pt-Mn and Pt-Cr alloys are paramagnetic.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 6; 983-992
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Recent Developments of the Bloch-Modified Ladder Theory
    Autorzy:
    Sormann, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929111.pdf
    Data publikacji:
    1993-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.70.Bj
    71.25.Pi
    Opis:
    One of the possible theoretical approaches for desribing the physics of electron-positron pairs in the inhomogeneous electron gas is the so-called "quasi-free" Bloch-modified ladder theory. Despite the success of this approach, it contains two very serious deficiencies, namely the complete neglect of the Bloch character of the electron and positron scattering states and of the electron-positron interaction potential. In this contribution, the importance of these Bloch effects for the Bloch-modified ladder theory results, especially for the momentum dependence of the positron enhancement in d-band metals, is demonstrated for the first time.
    Źródło:
    Acta Physica Polonica A; 1993, 83, 3; 381-390
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electronic Structure of KMgH$\text{}_{3}$, KMgH$\text{}_{2}$F, KMgF$\text{}_{3}$ with the Perovskite Structure
    Autorzy:
    Balawender, R.
    Gupta, M.
    Orgaz, E.
    Komorowski, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1943944.pdf
    Data publikacji:
    1995-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.20.Cf
    71.25.Pi
    Opis:
    The electronic structures of fluoroperovskite KMgF$\text{}_{3}$, hydridoperovskite KMgH$\text{}_{3}$ and the dihydrido-fluoro derivated KΜgH$\text{}_{2}$F have been investigated. The energy bands, density of electronic states and partial wave analysis of the density of electronic states have been determined by means of the non-self-consistent augmented plane wave method with the von Barth-Hedin parametrization for the exchange-correlation term. Our results indicate that all three compounds are ionic insulators. Replacing the hydrogen atom by fluorine atom leads to increasing in the energy gap.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 6; 1133-1141
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electron-Positron Enhancement in d-Metals Described by the Bloch-Modified Ladder Theory and the Local Density Approximation: a Comparative Study
    Autorzy:
    Sormann, H.
    Wallner, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933541.pdf
    Data publikacji:
    1995-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    78.70.Bj
    Opis:
    In this paper, we present a preliminary summary of our recent results on the enhancement of the electron-positron annihilation rate in d-band metals based on our recently published optimized quasi-free Bloch-modified ladder [QF-BML(opt.)] theory. This approach enables us to investigate the influence of the periodical lattice potential on the electron-positron annihilation in an approximative but nevertheless physically reasonable way. We used our theory for calculations of momentum-dependent enhancement factors belonging to electron states of different (s-, p-, d-) character in simple, transition and noble metals (Na, Cu, Pd, V). It is interesting to compare these new BML results with corresponding results obtained by the local density approximation (LDA) according to the work of Daniuk et al. We observe relatively strong differences between the BML and LDA enhancement factors for metals whose polarization process is dominated by s or p electrons. In such cases, we presume that the LDA approach has the tendency to overestimate the role of the more-localized d electrons in the polarization of the inhomogeneous electron gas. For transition metals whose physics is mainly determined by such d electrons, the discrepancies between BML and LDA enhancement results are significantly smaller.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 1; 225-235
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Angle-Resolved UV Photoemission from Single Crystals of AgPd Alloys
    Autorzy:
    Ilver, L.
    Nilsson, P. O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1924334.pdf
    Data publikacji:
    1993-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    79.60.Gs
    71.25.Pi
    Opis:
    The angular dependence of photoemission energy distributions were measured from single crystal, substitutional disordered alloys Ag$\text{}_{x}$Pd$\text{}_{1-x}$ with x = 0.97 and x = 0.90. The random hybridization between the Ag 5sp band and the Pd 4d state is discussed in terms of complex energies.
    Źródło:
    Acta Physica Polonica A; 1993, 83, 1; 125-132
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Residual Resistivity Due to Vacancies in Alkali Metals
    Autorzy:
    Gajjar, P. N.
    Thakore, B. Y.
    Luhar, J. S.
    Jani, A. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931622.pdf
    Data publikacji:
    1994-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.55.At
    72.15.-v
    71.25.Pi
    Opis:
    We have used a pseudopotential technique to examine the contribution of monovacancy, which is one of the point defects, to the resistivity of alkali metals. Two different forms of the bare-ion local pseudopotential, to describe the electron-ion interaction in metals, have been employed in the present work. Various forms of the dielectric function lave been used to incorporate the exchange and correlation effects among the conduction electrons. Varying effect of dielectric functions on the computed results is concluded while comparing our findings with other theoretical data.
    Źródło:
    Acta Physica Polonica A; 1994, 86, 3; 369-374
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electronic Structure Seen by Positrons in Extended and Reduced Zone Schemes
    Autorzy:
    Kontrym-Sznajd, G.
    Sormann, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933517.pdf
    Data publikacji:
    1995-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    71.60.+z
    78.70.Bj
    Opis:
    The influence of the positron on the momentum distribution of annihilation quanta is investigated. Basing on general considerations, we show that a noninteracting positron, which generally reduces electronic densities, may enlarge some particular electronic umklapp components. Numerical tests were performed for alkalis, Al, Cu and Pd by applying augmented plane wave band structure calculations. In the paper we discuss also the influence of this effect on the electron-positron densities after including the electron-positron correlation effects.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 1; 177-184
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Umklapp Components of the Positron Momentum Density Depending on Different Models for the Positron Wave Function
    Autorzy:
    Kontrym-Sznajd, G.
    Sormann, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933519.pdf
    Data publikacji:
    1995-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    71.60.+z
    78.70.Bj
    Opis:
    In this paper, we present a numerical investigation about the question how sensitively Fourier coefficients of the positron wave function ψ$\text{}_{+}$ react to different (and not too strong) changes of ψ$\text{}_{+}$. In order to obtain general information about this problem, we studied this sensitivity for several bcc and fcc metals and for different models of the positron wave function. Summarizing our results, we can say that this sensitivity is generally small (or at least moderate) for Fourier coefficients belonging to reciprocal lattice vectors G which lie nearest to the centre of the momentum space. For the outer vectors G, the amount of this sensitivity is strongly dependent on the crystal structure of the metal and on the special like of the change of the positron wave function.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 1; 185-192
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron Annihilation in Pd-Ag-H and Pd-Au-H Systems
    Autorzy:
    Dębowska, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1928991.pdf
    Data publikacji:
    1993-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.70.Bj
    71.25.Pi
    71.90.+q
    Opis:
    Positron annihilation method was used to study hydrogenated Pd$\text{}_{1-y}$Ag$\text{}_{y}$, and Pd$\text{}_{1-y}$Ag$\text{}_{y}$ alloys in α-phase. In both systems, insensitivity of the low-lying core states to the presence of hydrogen in the alloy was found. Rigid band mode1 appeared to be a useless description of the changes in the band occupation after hydrogen absorption. The results seem to indicate that the "capacity" of the low-lying H-Pd bonding states remains constant when the Ag or Au atoms are added to PdH$\text{}_{≈0.6}$, which can explain the existence of the limit to the summed up hydrogen and Ag(Au) concentration.Zatwie
    Źródło:
    Acta Physica Polonica A; 1993, 83, 3; 287-292
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature Dependence of Photofield Emission from Tungsten ⟨001⟩ Direction
    Autorzy:
    Radoń, T.
    Jaskólka, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945415.pdf
    Data publikacji:
    1996-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    79.60.Bm
    79.70.+q
    71.25.Pi
    Opis:
    The existence of a minimum lying by 0.2 eV above the Fermi level, in the band structure of the ⟨001⟩ direction of tungsten, has been confirmed at temperatures of 600÷800 K of the emitter. With increasing temperature a slight rise of the Fermi level in relation to the band structure has been observed.
    Źródło:
    Acta Physica Polonica A; 1996, 89, 5-6; 665-668
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Scalar Relativistic Spin Polarized Electronic Structure of Ferromagnetic fcc GdAl$\text{}_{2}$
    Autorzy:
    Borgieł, W.
    Deniszczyk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929823.pdf
    Data publikacji:
    1993-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.25.Pi
    75.30.-m
    75.50.Cc
    Opis:
    One-particle electronic states of ferromagnetic single crystal Laves phase GdAl$\text{}_{2}$ is calculated with the help of augmented spherical waves, based on density functional theory. Density of states, partial densities of states are presented. The behavior of the spectrum in the vicinity of the Fermi energy and the number of occupied states are discussed in detail.
    Źródło:
    Acta Physica Polonica A; 1993, 84, 6; 1071-1083
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Photoemission of Cd(0001) Using Synchrotron Radiation
    Autorzy:
    Sobczak, E.
    Nilsson, P. O.
    Karlsson, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920911.pdf
    Data publikacji:
    1992-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    79.60.Cn
    73.20.At
    71.25.Pi
    Opis:
    Photoemission spectra for the Cd(0001) surface in the Γ̅-M̅ azimuth were calculated using a multiple scattering method. The emission angle of the photoelectrons θ was kept constant and equal to 35°. The photon energy was varied from 20 eV to 27 eV. The self-consistent potential used in the calculations was generated by the scalar-relativistic LMTO method. A modified image potential for the surface barrier potential was applied. The photoemission spectra show a strong surface state peak at an energy of about 1 eV below the Fermi level.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 2; 337-339
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-14 z 14

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