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<title>vdwxc : README</title>
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<h5>Copyright (C) 2010-2012 ABINIT Group (Yann Pouillon)
<br>This file is distributed under the terms of the GNU General Public License, see
~abinit/COPYING or <a href="http://www.gnu.org/copyleft/gpl.txt">
http://www.gnu.org/copyleft/gpl.txt </a>.
<br> For the initials of contributors, see ~abinit/doc/developers/contributors.txt .
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<pre>

This directory, vdwxc, contains tests which exercise parts
of the ABINIT package, related to the use of van der Waals
exchange-correlation.
This file gives first a very brief description
of the tests, then a much longer one.

These tests are designed primarily to exercise parts of the code
quickly, NOT necessarily to give physically sensible results.
For tests of correctness, see directory physics (under development).
For greater speed, some tests are not run to full convergence.
Also the quality parameters (especially ecut) are sometimes minimal, i.e.
the calculations are underconverged.

A classification of the tests is provided now. Later, each test is described
in more detail, with accompanying notes and references (some of the notes
might have to be updated, due to the small possible drift related to improvement
of the accuracy of the code).

Tests 1 to 3 examine different exchange-correlation functionals related
to the vdW-DF approximations.

Tests 10 and 11 examine the approaches of Silvestrelli vdW-WF1 and vdW-WF2
respectively.

To run these tests, do the following:

0. Be sure that the perl script "run-standard-tests", in the main directory,
   has been generated from the primitive file "run-standard-tests.pl",
   thanks to the command "make perl"
   issued in ~abinit (see the installation notes on the Web).

1. Submit the "run-standard-tests" script, specifying a machine, and
   the keyword "vdwxc" (for Tests_vdwxc) and either
   the index of a test case, i.e.
   (run-standard-tests name_of_machine vdwxc 22) >& log_file
   or a whole range of test cases (two indices), i.e.
   (run-standard-tests name_of_machine vdwxc 02 08) >& log_file
   or, if you want to run all the test cases of this directory
   (run-standard-tests name_of_machine vdwxc) >& log_file
   This will send stdout and stderr to log_file.
   The script 'run-standard-tests', will create a subdirectory of ~abinit/tests/vdwxc,
   with the name_of_machine and the
   date, where all the results will be placed.

2. In that directory, you will find for each test case that you have
   run, a log file (with the name of the test case), an output
   file, but also a 'diff.xxx' file, automatically created by making
   a 'diff' with respect to the "Refs" subdirectory output files.
   It contains output files from a recent version of the ABINIT code.
   There may be large differences in timing but there should only
   be minor differences in the output of physical quantities.

3. There is also a global report file, generated by the use of the
   fldiff script. Its name is fldiff.report . See the last
   version of the  ~abinit/doc/install_notes/install** file
   in the Infos directory for information about the use of this file.
   This file is the most convenient for a quick look at the correctness
   of results. When the results are not correct, one has often to
   rely on the 'diff.xxx' file to understand what was going wrong.

**********

Test cases:

01. Argon FCC
    Test the vdW-DF1 functional.

02. Argon FCC
    Test the vdW-DF2 functional.

03. Argon FCC
    Test the C09x functional.

04. Argon FCC
    Test the vdW-DFT-D2 (Grimme) semi-empirical potential.

10. Argon FCC
    Test the approach of Silvestrelli to access van der Waals interactions.
    Test provided by Camilo Espejo and Yann Pouillon.

11. Argon FCC
     Test the approach of Ambrosetti and Silvestrelli to assess van der Waals interactions.   
     http://arxiv.org/abs/1111.6737
     Test provided by Camilo Espejo and Yann Pouillon.                         
</pre>
