Update README.rst

README.rst

@@ -19,3 +19,26 @@ Expensive operations are carried out by dedicated external libraries like
 applications and scales well when moving to an MPI cluster. D2O is open-source 
 software available under the GNU General Public License v3 (GPL-3). 
 
+Installation
+------------
+
+Requirements
+............
+
+*   `Python <http://www.python.org/>`_ (v2.7.x)
+*   `NumPy <http://www.numpy.org/>`_ 
+*   `mpi4py <https://bitbucket.org/mpi4py/mpi4py>`_ **optional**
+
+Installation on Ubuntu
+......................
+
+::
+        sudo pip install mpi4py
+
+::
+
+        git clone https://gitlab.mpcdf.mpg.de/ift/D2O.git
+        cd D2O
+        sudo python setup.py install 
+        cd ..
+