mpdf

The diffpy.mpdf package provides a convenient method for computing the magnetic PDF (mPDF) from magnetic structures and performing fits to neutron total scattering data. The mPDF is calculated by an MPDFcalculator object, which extracts the spin positions and spin vectors from a MagStructure object that the MPDFcalculator takes as input. The MagStructure object in turn can contain multiple MagSpecies objects, which generate magnetic configurations based on a diffpy.Structure object and a set of propagation vectors and basis vectors provided by the user. Alternatively, the user can manually define a magnetic unit cell that will be used to generate the magnetic structure, or the magnetic structure can be defined simply as lists of spin positions and spin vectors provided by the user.

../_images/mpdf_screenshot.png

This is an early release of mpdf, and the capabilities and documentation of the project will evolve. The DiffPy team encourages investigators to provide feedback, suggestions, and feature requests.

Getting Started

The diffpy.mpdf package requires Python 2.6 or 2.7 and the following software:

  • NumPy - numerical mathematics and fast array operations for Python
  • SciPy - scientific libraries for Python
  • matplotlib - python plotting library
  • diffpy.Structure - diffpy package for generating atomic structure
  • diffpy.srreal - diffpy package for calculating real-space quantities

See the mpdf license for terms and conditions of use.

Installation

The recommended way to install this package is through conda. For help installing conda, please visit https://www.continuum.io/downloads. Once conda is installed, you can follow the simple steps below to install diffpy.mpdf. You will also install the full diffpy-cmi suite along the way.

Step 1: Add the appropriate conda channels to your conda configuration.

conda config --add channels diffpy
conda config --add channels benfrandsen

These commands tell conda to look through these channels on the Anaconda cloud server to find the appropriate software.

Step 2 (recommended): Create and activate a conda environment for diffpy + diffpy.mpdf.

conda create --name diffpy python=2.7
source activate diffpy

Note that you can name the environment anything you choose by passing it a different name after the –name flag in the first command.

Step 3: Install diffpy.mpdf.

conda install diffpy.mpdf

Note that this will also install the full diffpy-cmi suite if it has not already been installed in this environment.

Alternative option: Install from the python package index.

If you prefer to use the python package index and have pip installed, please install the prerequisite software and then use the command

pip install diffpy.mpdf

Alternative option: Download and install from source.

If you prefer to install from source, you can also zip and download the entire package from PyPI or GitHub, then unzip the file and execute the following command from inside the unzipped directory

python setup.py install

Note that this will only work if all the dependencies are already properly installed.

Documentation

Please see http://pythonhosted.org/diffpy.mpdf/ for the documentation.

What next?

Explore the mpdf tutorial and examples on the CMI Exchange!