A program to calculate magnetic form factors for transition metal systems

✍ Scribed by L.A. Barnes; G.S. Chandler; B.N. Figgis; D.C. Khan

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 690 KB
• Volume: 36
• Category: Article
• ISSN: 0010-4655
• DOI: 10.1016/0010-4655(85)90026-8

✦ Synopsis

Title of program: MAGFAC operator contributions are evaluated using standard angular momenta relations. These non-zero matrix elements are ex-Catalogue number: AABR panded [5] in terms of spherical harmonics, Y,,,,, Condon-Shortley coefficients [4], C'(l, m; 1', m'), and the radial in-Program available from: CPC Program Library, Queen's Urn-tegrals (JL) and <EL) [4,5]. versity of Belfast, N. Ireland (see application form in this issue) The form factors are thus calculated for any reflection (h, k, 1) in the Cartesian system determined by the user. Computer: Cyber CDC72O; Installation: Western Australian Regional Computing Centre Restrictions on the complexity of the problem MAGFAC is restricted to Hartree-Fock level crystal field Programming language used: Fortran IV wavefunctions [3,6] for transition metal systems with a partially filled 3d shell. The structure of the program enables the case of High speed storage required: 170 K 4f electrons to be incorporated in a straightforward manner. The present dimensions restrict the input wavefunction to No. of lines in combined program and test deck: 2500 50 determinants, with 5 electrons or holes maximum for d electrons. The radial function is represented by a basis set of up Keywords: neutron scattering, magnetic form factor, spin, to 5 Slater type orbitals, and up to 350 reflections are allowed. orbital, spherical, asphencal, magnetization density Typical running time Nature of physicalproblem l'his varies widely from problem to problem. A typical run with MAGFAC calculates magnetic form factors for a transition 20 three-electron determinants and 340 reflections was accommetal ion under the influence of a crystal field. This can be plished in 16 s on the Cyber CDC72O. The test cases here all defined, in the formalism of Trammel [1], as the expectation took ~0.6 s. Compilation time is 12 s. value of the operator representing the magnetic interaction of the neutron with the ion at a particular lattice site. The References program calculates each Cartesian component of the form [1] G.T. Tranunell, Phys. Rev. 92 (1953) 1387.