pySpinW is a tool for calculating magnon energies and simulating scattering experiments

Details of its use can be found at www.spinw.org/pyspinw

Example

Here is an example of calculating dispersion curves for simple ferromagnetic chain in python:

from pyspinw import *

# Define the unit cell
unit_cell = UnitCell(1,1,1)

# Specify a magetic atom at (0,0,0), with moment (0,0,1)
x = LatticeSite(0, 0, 0, 0, 0, 1, name="X")

# Create a magnetic structure (this could include a spacegroup, or 
# supercell structure, but we don't do so here)
structure = Structure([x], unit_cell=unit_cell)

# A single exchange between atoms in neighbouring unit cells (in the x direction)
exchanges = [HeisenbergExchange(x, x, cell_offset=(1,0,0), j=-1)]

# Create a Hamiltonian object that holds things together 
hamiltonian = Hamiltonian(structure, exchanges)

# Define a path through q-space for out dispersion curve
path = Path([[0,0,0], [1,0,0]])

# Show the spaghetti plot, with constant energy smearing of 0.4
hamiltonian.spaghetti_plot(path, dE=0.4)

This should produce a plot like this:

New features in the python version

There are a number of features in pySpinW that did not exist in the MATLAB version.

• A viewer that lets you see magnetic structures and their data simultaneously
• Parameterisation of hamiltonians
• Saving of objects (note: we are still in alpha, so expect there to be changes in file format in the near future)
• Approximation of incommensurate structures
• Tools for working with spacegroups

Functional parity with SpinW

pySpinW is still in alpha, this means that a small number of features of SpinW are not present or complete in pySpinW and that some features are not considered stable.

Not fully ported:

• Fitting of incommensurate k-vectors (work in progress)
• Powder fitting tools (basic powder fitting available, but not all tools are ported yet)