MPI document strcture

docs/parallel/mpi.rst

@@ -1,6 +1,10 @@
+.. _sec-mpi:
+
 MPI parallel calculations
 =========================
 
+Architecture
+------------
 
 Groups
 ------
@@ -9,6 +13,36 @@ Groups
   calculations with spin polarisation and/or k-points.
 
 
+Solvers
+-------
+
+ScaLAPACK solvers
+^^^^^^^^^^^^^^^^^
+
+The `QR`, `DivideAndConquer` and `RelativelyRobust` dense ScaLAPACK
+eigensolvers are available. However, if possible, we suggest using the
+ELSI solvers for their better performance and capabilities.
+
 ELSI solvers
-------------
+^^^^^^^^^^^^
+
++--------------------+--------------------+--------------------+--------------------+
+|Solver              |Use case            |Scaling with atoms  |Eigenvalues         |
++--------------------+--------------------+--------------------+--------------------+
+|ELPA                |General (dense)     |O(N :sup:`3` )      |available           |
++--------------------+--------------------+--------------------+--------------------+
+|PEXSI               |General (sparse)    |O(N :sup:`2` ) --   |not available       |
+|                    |                    |O(N)                |                    |
++--------------------+--------------------+--------------------+--------------------+
+|NTPoly              |Better for gapped   |O(N)                |not available       |
+|                    |systems (sparse)    |                    |                    |
++--------------------+--------------------+--------------------+--------------------+
+
+
+Examples
+--------
+
+Transport calculations
+----------------------
 
+For :ref:`electronic transport <sec-transport>`, MPI parallelism is also supported.