Dear user of ABINIT (in short : ABINITioner),

If this is the first time that you have access to ABINIT, or that you receive an ABINIT announcement, welcome !

On the Web site, you will find a lot of things, including different versions of ABINIT, installation notes, release notes, help files (tutorial, list of input variables), pseudopotentials, some utilities, mailing lists, some documentation. Even more information on ABINIT is given directly in the package.

We will use the name ~ABINIT to refer to the directory that contains locally the ABINIT package, uncompressed.  ~ABINIT contains different subdirectories. Some of the files in the ~ABINIT/doc subdirectories are written in html, and are accessible also from the Web site : e.g. the tutorial and the list of all ABINIT input variables. The best entry point, after the installation, is likely the "new user's guide".

The logic of ABINIT version releases is as follows:
The full name of a version has three digits (for example, 5.7.3). The first digit is the slowly varying one (in average, it is changed each other year). It indicates the major efforts and trends in that version. At the level of 1.x.y ABINIT, the major effort was placed on the "ground-state" properties (total energy, forces, geometry optimisation, molecular dynamics ...). With version 2.x.y , response-function features (phonons, dielectric response, effective charges, interatomic force constants ...) were included. The main additional characteristics of version 3.x.y were the distribution under the GNU General Public Licence, the set-up of the documentation and help to the user through the Web site in html format, and the availability of GW capabilities. The version 4.x.y put a lot of effort in the speed of ABINIT (e.g. PAW), and its parallelisation. In version 5.x.y, plugins were added, and PAW fully developed (also with GW).

When additional features are present, the second digit in incremented. So versions 4.x started with 4.0 and finished at 4.6, with more and more features added. Version 5.6 was released in September 2008, and version 5.7 in January 2009. Two versions differing by the last (third) digit have the same capabilities, but one with the largest last digit is more debugged than the other : version 5.7.3 is more debugged than 5.7.2 or 5.7.0, but no new features has been added (so likely, no additional bug!).

As mentioned above, starting with version 3, ABINIT has been distributed under the GNU General Public Licence. The GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. To protect these rights, one needs to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.

Usually, a version of ABINIT is released only when it has been installed 'successfully' on 5 different platforms. A successful installation includes a battery of more than 500 tests, whose results are automatically analyzed (this does not garantee that the code is bug free, however, and the contribution of testers is crucial).

A last word : we strongly suggest that you register on the ABINIT announce mailing list (low traffic), and the forum mailing list. This is still, for the time being, the best way to keep in touch with the evolution of ABINIT.

Have fun with ABINIT !

Xavier and the ABINIT group.