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
    between June 2010 and September 2010. These release notes
    are relative to improvements of ABINITv6.4 with respect to v6.2.

    The list of contributors includes :
    D. Adams, B. Amadon, A. Berger, J.-M. Beuken, F. Bottin,
    P. Boulanger, F. Bruneval, C. Espejo, G.A. Franco, M. Giantomassi, X. Gonze, I. Hamada,
    F. Jollet, A. Lherbier, S. Miller, T. Nishimatsu, M. Oliveira, Y. Pouillon, AH. Romero,
    M. Torrent, M. Verstraete, D. Waroquiers, Z. Zanolli, 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 6.4, released on September 27, 2010.

    Changes with respect to version 6.2 :

    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 format of the DOS file has changed : the index field column has been suppressed. It is easier to plot this file
        with standard graphic packages.
        By M. Verstraete

    A.2 Removed a bug in the computation of the temperature-dependence of the gap (and electronic structure).
        The reference files for test v5#26, 27, 28 have been corrected.
        By P. Boulanger and X. Gonze

    A.3 Many different options have been added to the prtden variable. It contains the features previously activated by pawprtden.
        See v5#11 for prtden 2 (causes generation of a file _PAWDEN that contains the bulk
        valence charge density together with the PAW on-site contributions, and has the same format as the other density files
        (Test cases to be provided for prtden 3 to 6 !)
        By D. Waroquiers

    A.4 A numerical bug present in v6.4.1 has been fixed in v6.4.2 . It concerned GW-PAW calculations only,
        the computation of the head and wings of the susceptbility matrix at q=0.
        Expect the changes in the QP energies to be around tens of meV.
        Results for systems sampled at Gamma only were correct though.

    A.5 The default value for ecutwfn and ecutsigx is now set to ecut.

    __________________________________________________________________

    B.  Most noticeable achievements

    B.1 The computation of the RPA energy in the GW part of ABINIT is now available.
        Coded in the norm-conserving and PAW cases
        Several techniques have been implemented : use of logarithmic formula, use of numerical integration over the interaction.
        It can be combined with the extrapolar trick and the range separated Coulomb interactions.
        Test v6#99. Input variable gwrpacorr .
        By F. Bruneval

    B.2 Implementation of the GW Effective Energy Technique, by J.A. Berger .
        See J.A. Berger, L. Reining, and F. Sottile, Phys. Rev. B 82, 041103(R) (2010).
        Presently only norm-conserving pseudos are supported.
        Parallel implementation on k-points and occupied states (gwpara=1) but not yet on memory (gwpara=2).
        Related input variables (not operational yet) gw_EET and gw_EET_nband.
        Automatic test Tv6#90
        Work by J.A. Berger, some help by M. Giantomassi.

    B.3 Several advanced features of the GW part of ABINIT can now be used safely.
        In particular QPSCGW + PAW is OK, as well as self-consistent COHSEX + PAW.
        Extrapolar works with SCGW, also with PAW.
        SCGW has now been implemented with symmetries (HF, COHSEX, SEX), and use of
        hermitianity (speed up of the calculations).
        The memory is better controlled, thanks to the gwmem input variable.
        Two different FFT meshes defined by ecuteps and ecusigx are used to calculate the
        matrix elements the exchange and the correlation part of the self-energy, respectively.
        A new optdriver level has been addded for performing self-consistent GW calculations.
        Related input variables gw_nstep, gw_sctype, gw_sctype_name, gw_toldfeig.
        Work by M. Giantomassi

    B.4 The capability to compute the U or J values, within the DFT+U (LDA or GGA) approach (with PAW, also spin-polarized),
        according to the method of Coccocioni and De Gironcoli (2005), is available in production.
        Input variable : macro_uj, pawujat, pawujv, and pawujrad.
        Automatic tests : Tv5#38, 39, Tv6#41
        Work by D. Adams and B. Amadon

    B.5 Print out VASP-style POSCAR and FORCES files, for use with PHON or frophon codes for frozen phonon calculations.
        Input variable prtposcar. See also the script extras/post_processing/phondisp2abi.py for easy use with PHON or
        equivalents (generates dataset inputs for abinit runs).
        Test v6#100.
        By M. Verstraete.

    B.6 The distribution of processors in the FFT/Band/k point parallelism can be found automatically.
        Input variable : paral_kgb .
        Work by F. Jollet

    __________________________________________________________________

    C. Changes for the developers

    C.1 Shiva, a new slave for the test farm has been set up : it tests the
        distcheck (creation of the distribution package, and test of this
        distribution package). It tests also the creation of html files. It
        makes sure as well that configure options which are rarely used do
        not break the build.
        By J.-M. Beuken, Y. Pouillon, X. Gonze

    C.2 The use of the FOX library is now tested automatically. A new directory tests/fox has been created
        for this purpose, with two tests for pseudopotential files written in xml. Should be generalized for all slaves.
        By M. Verstraete, J.-M. Beuken, X. Gonze

    C.3 There is an 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 accommodate the images (above gstate.F90).
        New tests of previous implementations were created, v5#02, for ionmov 2,3,20 .
        Some other tests were reorganised, e.g. v6#03, 04, 05 were combined.
        By G.A. Franco .

    __________________________________________________________________

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

    D.1 Finite electric field calculations can now take advantage of symmetries.
        (On top of PAW + parallel, that was announced in v6.2).
        Tv6#42 and 43
        By J. Zwanziger

    D.2 The use of Density Functional Perturbation Theory with PAW
        (phonons and electric field) is in progress,
        the test Tv6#56 has been created.
        by M. Torrent, F. Jollet and J. Zwanziger.

    D.3 Print out geometry (_BLZTRP_GEOM) and eigenenergy (_BLZTRP_EIGEN) files for the
        BoltzTraP code by Georg Madsen
        (computation of transport properties) is now available.
        Input variable prtbltztrp.
        Test v6#11 .
        By M. Verstraete.

    D.4 Self-consistent phonon calculations calculations have begun to be implemented, by M. Verstraete.
        See Souvatzis et al, Phys. Rev. Lett. 100, 095901 (2008) ; Souvatzis et al, Computational Materials Science 18, 184304 (2008).
        Documentation should be provided (input variable outscphon not described ?).
        Test v5 #88
        Input variables : scphon_temp and scphon_supercell

    D.5 Tests of the reading of pseudopotential files written in xml are now provided.
         Done using the FOX library. See tests/fox#01 and 02.
         By M. Verstraete.

    D.6 The use of LDA+Dynamical Mean Field Theory is in progress.
        (see D.7 of the 6.2 release notes)
        By B. Amadon

    D.7 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.
        New input variable pitransform
        Allowed by imgmov=9 (Langevin dynamics), imgmov=13 (chain of thermostats).
        New test (fake at present) : Tv6#26
        By G. Geneste and X. Gonze.

    D.8 On-going effort to provide vdW functionals for ABINIT.
         Silvestrelli approach is now in production.
         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.
         Work by C. Espejo, Y. Pouillon, AH. Romero and X. Gonze.

    D.9 The Tran-Blaha meta-GGA is available
        See the automatic test Tlibxc#09
        By M. Oliveira, A. Lherbier and X. Gonze.

    D.10 A fine grid method has been introduced to treat electron-phonon coupling (not functional yet).
         (see also point D.3 of 6.2  release_notes )
         Input variable kptrlatt_fine (not yet documented).
         Tv6#77 . Mentioned not to work yet (tests/v6/README) ?
         By M. Verstraete

    D.11 Work in progress : addition of Zeeman field (non-collinear), using the zeemanfield
         input variable. The documentation of the latter is still incomplete.
         A fake test has been set up v6#17.
         By X. Gonze, for K. Delaney and E. Bousquet.

    D.12 Input variable asr=5 has been added.
         By M. Verstraete

    D.13 A genetic algorithm to find new structures is under development.
         By AH. Romero and X. Gonze

    D.14 The configure script now displays environment variables at the
         beginning of its output when they override the settings of the config
         file. This is useful to address build-time platform-specific issues.
         By Y. Pouillon

    D.15 A new detection mechanism for external libraries (DFT, FFT, GPU,
         linear algebra, math, MPI, timer, transferable I/O), codename
         "connector", is currently under test. See the output of
         "configure --help" for details.
         By Y. Pouillon

    D.16 The tutorial GW1 has been updated and cleaned, to contain up-to-date information.

    D.17 Numerous miscellaneous bug fixes (to the sources, as well as to the build system, including the plug-ins),
         and improvements of documentation by
         J.-M. Beuken, F. Bottin, M. Giantomassi, I. Hamada, Steven Miller, T. Nishimatsu, Y. Pouillon, Tim Robinson, M. Torrent,
         M. Verstraete, Z. Zanolli, J. Zwanziger