Release notes

##### Copyright (C) 2010-2021 ABINIT group (XG)
This file is distributed under the terms of the GNU General Public License, see ~abinit/COPYING or http://www.gnu.org/copyleft/gpl.txt .
For the initials of contributors, see ~abinit/doc/developers/contributors.txt .

    Many thanks to the contributors to the ABINIT project
    February 2011 and June 2011. These release notes
    are relative to improvements of ABINITv6.8 with respect to v6.6.

    The list of contributors includes :
    F. Abreu, B. Amadon, A. Berger, J.-M. Beuken, F. Bruneval, D. Caliste, K. Delaney, C. Espejo,
    G.A. Franco, G. Geneste, M. Giantomassi, X. Gonze, Jiawang Hong, A. Jacques,
    L. He, A. Knyazev, S. Le Roux, A. Lherbier, F. Liu, M. Mancini, T. Nishimatsu, M. Oliveira,
    S. Ponce, Y. Pouillon, G.-M. Rignanese, A. Romero,
    M. Torrent, M. Stankovski, M. Verstraete, D. Waroquiers, J. Zwanziger .

    It is worth to read carefully
    all the modifications that are mentioned in the present file,
    and examine the links to help files or test cases ...
    This might take some time ...
    (Please note the WARNINGS !)

    Xavier

    __________________________________________________________________

    Version 6.8, released on June 27, 2011.

    Changes with respect to version 6.6 :

    A. WARNINGS.
    B. Most noticeable achievements (for users)
    C. Changes in the package, for developers
    D. Other changes (or on-going developments, not finalized)

    __________________________________________________________________

    A.  WARNINGS AND IMPORTANT REMARKS

    A.1 The default value for optforces has been changed (to 2).

    __________________________________________________________________

    B.  Most noticeable achievements

    B.1 The meta-GGA in the LibXC exchange-correlation library can now be used with ABINIT,
        in the norm-conserving case (not yet PAW), in the spin-non-polarized and collinear spin-polarized case
        (not yet non-collinear case).
        Some problems with the self-consistency are still present, though mostly for large cells and/or
        systems with a low symmetry.
        See the input variable ixc, and tests v6#33, libxc#06,07,08, and the associated comments in the libxc README.
        Work done by A. Lherbier and M. Oliveira.

    B.2 The GGA XC kernels from libxc can now be used with ABINIT,
       in the norm-conserving case and in the PAW case (only if pawxcdev=0 is set in input file),
       in the spin-non-polarized and collinear spin-polarized case
       (not yet non-collinear case).
       See the input variable ixc, and tests libxc#11, 12, 13
       By F. Liu, L. He, G.-M. Rignanese and Marc Torrent

    B.3 PAW+libxc is now allowed, see test libxc#10 (prepared by JZwanziger).
       To be used together with ATOMPAW+LibXC
       Work by M. Torrent

    B.4 A GUI for ABINIT has been set-up. It is available in the subdirectory "gui". Please, consult the README file
        for some instruction on how to use it.
        Work done by F. Abreu. Integrated in the build system by Y. Pouillon.

    B.5 The definition of the set of q points (for phonon calculations) for different datasets can now be done in the same
        spirit as for the generation of k points, that is,
        based on the input of a homogeneous grid of points.
        Related input variables : qptopt, ngqpt, nshiftq, shiftq, qptrlatt, iqpt.
        By X. Gonze
        See the automatic tests Tv6#35 and 78.

    B.6 The computation of the temperature-dependence of the electronic structure
        within the rigid-ion approximation (DFPT implementation, improving upon the Allen-Heine-Cardona approach)
        has been parallelized, and is much easier to use than before, thanks to modifications
        of ANADDB (input variable thmflag 5 to 8). An imaginary shift of the difference of energy
        (input variable elph2_imagden)
        allows to avoid the divergence of the denominator.
        By X. Gonze
        See automatic tests v6#37-40 and v6#68-69. And paral#AB for the parallelism.

    B.7 RPA calculations can be done now with extrapolar trick, saving a large amount of CPU time.
        The parallelism for the RPA functional with numerical integration has been implemented.
        Test cases are still to be provided.
        By F. Bruneval

    __________________________________________________________________

    C. Changes for the developers

    C.1 A new subdirectory of tests has been introduced, called "unitary". At present only FFT are tested.
        The purpose is to be able to test quickly a large number of options in a subset of routines
        that form an inner library of ABINIT.
        By M. Giantomassi

    C.2 A link checker has been activated, to enforce correctness of the hyperlinks in the HTML documentation of ABINIT.
        NOTE : It detects correctly all the broken links with target INSIDE of the ABINIT package.
        The correct detection of the broken links OUTSIDE of the ABINIT package is problematic,
        as they do not depend on us, and some Web site can be temporarily down. So, the check of
        external links has not been activated.
        By J.-M. Beuken.

    C.3 Woopy is a new slave for the test farm, under Windows.
        A new on-demand mechanism for testing ABINIT on the Web has been set-up, with address
        http://wwwold.abinit.org/on_demand
        The new slave ktulu is also available, to test debian/ubuntu packages.
        By J.-M. Beuken, and A. Jacques.

    C.4 Introduced a new subdirectory of tests, called tutoplugs, for testing the plugins when used in tutorials.
        By X. Gonze

    __________________________________________________________________

    D.  Other changes
    (or on-going developments, not yet finalized).

    D.1 A new automatic test (Tv6#94) and new input variables (bs_hayd_term and bs_nstates)
        have been introduced for the Bethe-Salpeter Equation part of ABINIT.
        Work in progress :  model dielectric function, Haydock approach,
        the potting of excitons, the Haydock method for pseudo Hermitian matrices,
        approximated DOS with Haydock method, post-processing tools for BSE calculations,
        BSE with collinear spin.
        Test cases to be provided ...
        By M. Giantomassi.

    D.2 The input variable vdw_nfrag and vdw_typfrag have been introduced,
        related to Silvestrelli approach to van der Waals interactions.
        Also, added spin polarizarion support for vdW-Wannier.
        This is in the frame of an on-going effort to provide vdW functionals for ABINIT.
        Also, on-going effort to have VdW-DF interfaced with ABINIT.
        Work by C. Espejo, Y. Pouillon, AH. Romero and X. Gonze.

    D.3 New input variables getpawden and irdpawden have been introduced.
        No documentation and no tests provided though ...

    D.4 New input variables cd_halfway_freq, cd_max_freq, cd_subset_freq,
        gw_use_freqre_tangrid have been introduced.
        See the test case libxc#14 to be activated soon.

    D.5 Phonon calculations using DFPT can now be done reliably with the PAW methodology,
       for the insulating case. This is still in beta testing. Some systems (with peculiar symetries)
       may not work.
       The metal case is operational (under the same conditions), except for q=0 (not fully implemented).
       The electric field response was already available previously.
       Still, for the time being, mixing of electric field and atomic displacement is not allowed.
       Work done by M. Torrent.
       See the test v6#62.

    D.6 On-going big restructuration of the routines involved in the change
        of the atomic coordinates and cell parameters (called by gstate.F90, linke brdmin.F90), also coupled with on-going
        changes to accomodate the images (above gstate.F90).
        Defines the use of NETCDF files, also ETSF-IO , for the restarts.
        See section C.3 of v6.4 release notes.
        By G.A. Franco .

    D.7 Atomic projection of the phonon band structure.
        See test v6#76, with input variables natprj_bs and iatprj_bs .
        By M. Verstraete.

    D.8 Add support for acml (4.4.0) in the build system
        By A. Jacques.

    D.9 Introduce occopt=8, with linearly changing occupation numbers between two limits.
         By X. Gonze.

    D.10 Work on the interfacing with xyz , poscar and CML files.
         By M. Verstraete.

    D.11 A genetic algorithm to find new structures is under development.
         (see D.13 of the 6.4 release notes)
         By AH. Romero and X. Gonze

    D.12 Memory optimization of the mrgddb tool
         By S. Poncé.

    D.13 Automatic computation of mqgrid (default is 0).
         By D. Waroquiers

    D.14 Work on library extraction.
         By D. Caliste

    D.15 Work on the input variable zeemanfield.
         By Kris Delaney.

    D.16 Work on the Effective Energy Technique by A. Berger.

    D.17 Added directory psps to interface with the pseudopotential generation and testing project.
         Also populated with some scripts.
         By A. Jacques, D. Waroquiers, M. Stankovski, and X. Gonze.

    D.18 Work in progress for the implementation of the Path Integral Molecular Dynamics algorithm for the
         ionic degrees of freedom, combined with DFT for the electronic degrees of freedom.
         Also, parallelism over the images.
         (see D.7 of the 6.4 release notes)
         By G. Geneste and M. Torrent

    D.19 The use of an extrapolation scheme to decrease the number of k-points needed for Berry phase
         calculations, finite electric fields and Raman intensity is in progress.
         Test v6#20 . Input variable berrystep.
         By S. Le Roux.

    D.20 The use of LDA+Dynamical Mean Field Theory is in progress.
         (see D.6 of the 6.4 release notes)
         Test v6#51.
         By B. Amadon

    D.21 On-going effort to provide vdW functionals for ABINIT.
         Silvestrelli approach is working.
         See input variables vdw_xc (=10 for Silvestrelli approach), vdw_nwan and vdw_supercell .
         Also, the XC functional C09 (ixc 24), for use with the Silvestrelli approach, has been coded.
         Available in v6#12, 13.
         Also, a new directory to test vdwxc has been created. At present Tvdwxc#10 is working.
         (see D.7 of the 6.4 release notes)
         Work by C. Espejo, Y. Pouillon, AH. Romero and X. Gonze.

    D.22 Work on SCPhonons going on.
         By M. Verstraete

    D.23 Related to B.3, the maximal number of datasets that can be treated by ABINIT has been
        increased from 99 to 9999. In a double-loop case, the maximum number for the
        first (outer) loop index is 999, while for the second (inner) loop it is 9.
        By X. Gonze
        See the automatic tests Tv6#34.

    D.24 Numerous miscellaneous bug fixes (to the sources, as well as to the build system, including the plug-ins),
         and improvements of documentation by
         A. Berger, J.-M. Beuken, F. Bruneval, D. Caliste,
         G.A. Franco, M. Giantomassi, X. Gonze, Jiawang Hong, A. Knyazev, A. Jacques, S. Le Roux,
         A. Lherbier, M. Mancini, T. Nishimatsu, S. Ponce, Y. Pouillon, G.-M. Rignanese,
         M. Torrent, M. Stankovski, M. Verstraete, J. Zwanziger .