Magnetic and electronic properties of disordered (Gd 1-xYx) 7Pd 3alloys : theoretical study

The ab initio study of electronic and magnetic properties of (Gd1xYx)7Pd3 alloys are presented. The electronic structure calculations were performed using FP-LAPW method. Basing on the ground-state single-electron results the many particle s f model for disordered alloy with strongly correlated band electrons was parameterized. The concentration dependence of the band structure, magnetic moment, and the Curie temperature is presented and discussed in reference to experimental data

Effect of noncollinear magnetic order on the hyperfine interactions in Pt3Fe

The investigations of the hyperfine interactions in Pt3Fe with the noncollinear magnetic order by means of ab initio methods are presented. It is shown that the ground state magnetic order of Pt3Fe is of noncollinear character. Electric field gradient and hyperfine magnetic field at 57Fe nucleus were calculated and their dependence on the strength of Coulomb correlation interaction is discussed. The calculated values of electric field gradient correspond with the experimental data and the best agreement was found when the enhanced Coulomb correlation interaction for 3d-states of Fe was considered. Lattice, local valence electron (3d, 4p) and weakly bound 3p semicore electron contributions to electric field gradient are separated out and discussed

Ab initio study of electronic structure and magnetic properties of Gd(Ni 1-xFex)3 alloys

We present the ab initio investigations of the electronic and magnetic properties of magnetocaloric Gd(Ni1xFex)3 alloys. To simulate fractional concentrations the supercell approach was implemented and di erent con gurations of iron atoms were considered. Energetical analysis of site preference and magnetic order was performed. The concentration dependence of the averaged total and local magnetic moments and of the valence band photoemission spectra are presented and discussed in reference to experimental data

Phase diagram calculations for the ZnSe-BeSe system by first-principles base thermodynamic Monte Carlo integration

Poprzedni tytuł czasopisma: Informatyka w Technologii Materiałów (2001-2005)The T-x phase diagram of Zn1-xBexSe alloy is calculated by means of ab initio method supplemented with the lattice Ising-like model cluster expansion approach and the Monte Carlo thermodynamic computations. Presented results confirm the high quality of mapping of disordered alloy onto the lattice Hamiltonian. The calculated phase diagram shows the asymmetric miscibility gap with the upper critical solution temperature equal to 860 K (1020 K) when the lattice vibrations are included (excluded) in the free energy of the system. We have proved that below the room temperature the miscibility of ZnSe and BeSe phases is possible only in the narrow range of concentration near the x = 0 and 1. At elevated temperatures the two phases are more capable to be mixed over the wider concentration range on the Zn-rich side of phase diagram

Ab initio study of electronic and magnetic structure and structural phase transition of (Fe 1-xMn x) 2P 1-yGe y alloys

The paper presents results of the ab initio electronic structure calculations performed for the (Fe0:5Mn0:5)2P0:67Ge0:33 alloy, a member of (Fe1xMnx)2P1yGey family of alloys showing a giant magnetocaloric e ffect. Calculations con rmed the strong relationship between the magnetic state and crystal structure of the alloy. To investigate the isostructural phase transition driven by external magnetic eld observed in (Fe0:9Mn1:1)P0:8Ge0:2 we utilized the xed spin moment approach. Total energy analysis con rmed the occurrence of isostructural phase transition

First principles phase diagram calculations for the CdSe-CdS wurtzite, zincblende and rock-salt structures

The phase diagrams of CdSe1-xSx alloys were calculated for three different crystal structure types: wurtzite (B4); zinc-blende (B3); and rocksalt (B1). Ab initio calculations of supercell formation energies were fit to cluster expansion Hamiltonians, and Monte Carlo simulations were used to calculate finite temperature phase relations. The calculated phase diagrams have symmetric miscibility gaps for B3 and B4 structure types and a slightly asymmetric diagram for B1 structure. Excess vibrational contributions to the free energy were included, and with these, calculated consolute temperatures are: 270 K for B4; 300 K for B3; and 270 K for B1. Calculated consolute temperatures for all structures are in good quantitative agreement with experimental data

Effect of Noncollinear Magnetic Order on the Hyperfine Interactions in Pt 3

The investigations of the hyperfine interactions in Pt3Fe with the noncollinear magnetic order by means of ab initio methods are presented. It is shown that the ground state magnetic order of Pt3Fe is of noncollinear character. Electric field gradient and hyperfine magnetic field at 57Fe nucleus were calculated and their dependence on the strength of Coulomb correlation interaction is discussed. The calculated values of electric field gradient correspond with the experimental data and the best agreement was found when the enhanced Coulomb correlation interaction for 3d-states of Fe was considered. Lattice, local valence electron (3d, 4p) and weakly bound 3p semicore electron contributions to electric field gradient are separated out and discussed

Avian reticuloendotheliosis in chickens – an update on disease occurrence and clinical course

Avian reticuloendotheliosis (RE) represents an important immunosuppressive disease of poultry. The occurrence of RE in both chickens and turkeys has an immunosuppressive effect and may lead to vaccination failures. Avian reticuloendotheliosis virus (REV) is widely distributed in different kinds of birds, causing subclinical infections. Another important issue adhering to this disease is contamination of vaccines against fowl pox (FP) and Marek’s disease (MD) with REV. The capability of REV to integrate into the genome of other larger DNA viruses complicates its diagnosis and prevention. There are no efficient vaccines against RE nor treatment, which also complicates how to limit its impact on poultry farming. This paper reviews the current state of knowledge of this important immunosuppressive agent of poultry emphasising the importance of this problem in terms of diagnosis of RE

Estimation of error for the solution of system of linear equations and application of the improved summation in algorithms of the linear algebra

In the paper an analysis of errors of the solution of system of the nonsingular linear equations is given. The numerically stable algorithm, implemented in the floating point arithmetics available in modern computers, is applied.&nbsp