diffpy.Structure - simple storage and manipulation of crystal structures

The diffpy.Structure package provides simple crystal structure operation
such as calculations of distances or angles from fractional coordinates.
It also provides imports and exports in several structure file formats
and space group definitions and utilities for symmetry expansion and 
generation of symmetry constraints on positions and thermal factors.

To learn more about diffpy.Structure library, see the examples directory
included in this distribution or the API documentation at

    http://docs.danse.us/diffraction/diffpy.Structure


REQUIREMENTS

The diffpy.Structure requires Python 2.5 and the following external software:

    setuptools  -- software distribution tools for Python
    numpy       -- numerical mathematics and fast array operations for Python

On Ubuntu Linux the required software can be easily installed using
the system package manager:

    sudo aptitude install \
        python-setuptools python-numpy

For other Linux distributions use their respective package manager; note
the packages may have slightly different names.  diffpy.Structure should work
on other Unix-like operating systems and on Mac as well.  Please, search the
web for instructions how to install external dependencies on your particular
system.


INSTALLATION

To install the diffpy.Structure package:

    python setup.py install

By default the files are installed in the system directories, which are
usually only writeable by the root.  See the usage info 
"./setup.py install --help" for options to install as a normal user under
different location.  Note that installation to non-standard directories may
require adjustments to the PATH and PYTHONPATH environment variables.

The Python setuptools library provides "easy_install" script, which can
be used to update diffpy.Structure installation or even to perform a new
install without explicit need to download and unzip the code:

    easy_install -U diffpy.Structure

This checks the package repository at http://www.diffpy.org/packages/
for any newer releases of diffpy.Structure and if present, it updates the
installation.  The easy_install can be also used to get in sync with the
latest development sources in the subversion repository:

    easy_install -U \
        svn://svn@danse.us/diffraction/diffraction/diffpy.Structure/trunk


CONTACTS

For more information on diffpy.Structure please visit the project web-page:

    http://www.diffpy.org/

or email Prof. Simon Billinge at sb2896@columbia.edu

Last modified $Date$