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3 Overview

You define the lattice using the lattice parameters a,b,c,alpha,beta,gamma and the positions of all the magnetic ions of the symmetric unit cell. The program works out what are the nearest neighbour bonds, next nearest neighbours, etc. You only need to specify how strong these are, and you choose a suitable hamiltonian.

Possible hamiltonians include:

  1. Super exchange with up to three different magnetic interaction pathway's (J's).
  2. the Zeeman term.
  3. Single-ion anisotropy, uniform, or canted along local crystal field axes.
  4. Long-range dipole-dipole interactions, using the reaction field method, or truncated sums (use with care). The Eward sum method has been implemented but needs to be optimised and tested.
  5. Dzyaloshinky Moriya interactions.

You can simulate one, two and three dimensional systems by specifying the appropriate periodic boundary conditions, and ising, xy- and Heisenberg spins.

The program returns the relevant thermodynamic parameters, the energy (E), specific heat (Cv), total absolute magnetisation (|M|), the total magnetisation in each spin dimension (M_i, i=1..D), the magnetic susceptibilities (Chi_i), and the Binder cumulant (BC). Optionally spinner saves the last generated magnetic structure, in a file with the extension '.state'. This file can be read by the program respin which can calculate the chiral structure, and correlation functions. The '.state' file can also be converted to the '.vect' format for viewing with Geomview.

The best way to learn using the program is probably by example. A number of example configuration files are included in the examples directory, they will also be discussed here.