The EXCITING FP-LAPW Code

A full-potential linearised augmented-plane wave (FP-LAPW) code with many advanced features. Written mainly at Karl-Franzens-Universität Graz as a milestone of the EXCITING EU Research and Training Network, the code is designed to be as developer-friendly as possible so that new developments in the field of density functional theory (DFT) can be added quickly and reliably. The code is freely available under the GNU General Public License.

General
• FP-LAPW basis with local-orbitals
• APW radial derivative matching to arbitrary orders at muffin-tin surface (super-LAPW, etc.)
• Arbitrary number of local-orbitals allowed (all core states can be made valence for example)
• Every element in the periodic table available
• Total energies resolved into components
• LSDA and GGA functionals available
• Core states treated with the radial Dirac equation
• Simple to use: just one input file required with all input parameters optional
• Multiple tasks can be run consecutively

Structure and symmetry
• Determination of lattice and crystal symmetry groups from input lattice and atomic coordinates
• Determination of atomic coordinates from space group data (with the Spacegroup utility)
• XCrysDen and V_Sim file output (with the Spacegroup utility)
• Automatic reduction from conventional to primitive unit cell
• Automatic determination of muffin-tin radii
• Full symmetrisation of density and magnetisation and their conjugate fields
• Automatic determination and reduction of the k-point set

Magnetism
• Spin polarised calculations performed in the most general way: only (n(r); m(r)) and (v_s(r); B_s(r)) are referred to in the code
• Spin symmetry broken by infinitesimal external fields
• Spin-orbit coupling (SOC) included in second-variational scheme
• Non-collinear magnetism (NCM) with arbitrary on-site magnetic fields
• Fixed spin-moment calculations (with SOC and NCM)
• Spin-spirals for any q-vector (conical spirals are still experimental)

Plotting
• Band structure plotting with angular momentum character
• Total and partial density of states with irreducible representation projection
• Charge density plotting (1/2/3D)
• Plotting of exchange-correlation and Coulomb potentials (1/2/3D)
• Electron localisation function (ELF) plotting (1/2/3D)
• Fermi surface plotting (3D)
• Magnetisation plots (2/3D)
• Plotting of exchange-correlation magnetic field, B_xc (2/3D)
• Plotting of ∇⋅B_xc (1/2/3D)
• Wavefunction plotting (1/2/3D)
• Electric field (E=-&nabla V) plotting (1/2/3D)
• Simple scanning tunnelling microscopy (STM) imaging based on the local density of states (LDOS) (experimental)

Forces
• Forces - including incomplete basis set (IBS) and core corrections
• Forces work with spin-orbit coupling and non-collinear magnetism
• Structural optimisation
• Phonons for arbitrary q-vectors (experimental)
• Phonon dispersion and density of states
• Phonon calculations can be distributed across networked computers

Advanced
• Exact exchange (EXX) optimised effective potential (OEP) method (with SOC and NCM) (experimental)
• EXX energies (with SOC and NCM) (experimental)
• Hartree-Fock for solids (with SOC and NCM) (experimental)
• LDA+U: fully localised limit (FLL), around mean field (AFM) and interpolation between the two; works with SOC, NCM and spin-spirals (experimental)
• Reduced density matrix functional theory (RDMFT) for solids (experimental)

Miscellaneous
• Mössbauer hyperfine parameters: isomer shift, EFG and hyperfine contact fields (experimental)
• First-order optical response
• Kerr angle and Magneto-Optic Kerr Effect (MOKE) output (experimental)
• Generalised DFT correction of L. Fritsche and Y. M. Gu, Phys. Rev. B 48, 4250 (1993) (experimental)
• L, S, and J expectation values
• Effective mass tensor for any state
• Equation of state fitting (with the EOS utility)

Programming
• Clean, simple code structure - ideal for development
• OpenMP parallelisation over k-vectors
• Strict Fortran 90 compliance
• Only one language used
• Free-form style input file
• Full LaTeX documentation included with every subroutine
• Users' and Developers' guides

The EXCITING Code Manual is available, as is a manual for the Spacegroup utility. You can ask and answer questions in the EXCITING forums on SourceForge.net but please consult the EXCITING frequently asked questions page first. A mailing list is available for notification of new releases, features and bugs in the code, and a Wiki which can be edited. There is also a collection of useful links here. If you would like a particular feature to be implemented then you can either do it yourself, which is the preferred option, or submit a feature request on SourceForge.

Citation of the code is not mandatory but would be appreciated by the contributors - a reference to this website will suffice. We also recommend that the input files used be made available to other researchers.

Groups and individuals are actively encouraged to develop and release their own specialised versions of the EXCITING code. However, in order to avoid any confusion, please use a different name for your version of the code. We suggest you append the name of your location to EXCITING, for example: EXCITING-Uppsala

EXCITING is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. EXCITING is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with EXCITING; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

EXCITING is still in its beta state so check the consistency of your results carefully! Features marked as experimental are for testing purposes only and should NOT be used for production work. The latest releases can be downloaded from SourceForge.net.

exciting-0.9.151
-fixed serious bug discovered by C. Koehler in the density symmetrisation routine - this affected a limited number of spacegroups (like that in the B12 example), and typically produced a warning about the total charge
-no other changes

exciting-0.9.150
-Reduced density matrix functional theory (RDMFT) now available thanks to S. Sharma, see arXiv:0801.3787v1 [cond-mat.mtrl-sci] (experimental)
-Bug in symmetrisation of non-collinear magnetisation found and fixed by F. Cricchio, F. Bultmark and L. Nordström
-F. Bultmark added new input variable reducebf which reduces the external magnetic field by this value after each iteration, thus at the end of the s.c. loop the external magnetic fields are zero. By default there is no reduction. See the manual for details.
-OEP calculations are now considerably faster
-Hartree-Fock now works properly with magnetism
-Alexey Baranov suggested an improvement of the cubic spline routine and submitted an example on how to obtain perfectly smooth ELF plots (see Ru-ELF)
-various minor changes to formatting of output files
-added more code documentation
-minor improvements and optimisations

exciting-0.9.146-149
-internal releases only

exciting-0.9.145
-fixed bug in non-collinear LDA+U, spotted by Francesco Cricchio and Lars Nordström, and simplified code
-fixed problem which occurs with Intel Fortran version 10, thanks to C. Koehler
-made the code thread safe for FFTW, thanks again to C. Koehler for pointing this out
-minor optimisations
-new mailing list available for developers, administered by C. Meisenbichler

exciting-0.9.140-144
-internal releases only

exciting-0.9.139
-fixed bug which prevented FSM calculations converging (no other changes)

exciting-0.9.138
-LDA+U now available thanks to the considerable efforts of Francesco Cricchio, Fredrik Bultmark and Lars Nordström, as well as the kind hospitality of the group of Hardy Gross. There are three different methods implemented: 1. fully localised limit (FLL), 2. around mean field (AFM), and 3. an interpolation between the two (see PRB 67, 153106 (2003) and PRB 52, R5467 (1995)). The implementation is fully non-collinear and works with spin-orbit coupling and spin-spirals. It is currently an experimental feature. See the LDA+U examples and documentation for details on how to use it.
-F. Cricchio added a fixed local moments feature, so that the moment in every muffin-tin can be fixed. Note that because of this, the variable fixspin has changed from Boolean to integer. See the manual for details.
-planar spin-spirals are no longer experimental and may be used for production, thanks to extensive testing by F. Cricchio (the conical kind still need more checking). FC and L. Nordström also found and fixed a bug in the spin-spiral symmetry setup.
-after extensive checking Fritz Körmann found a problem with the GGA implementation which has now been fixed: may have a small effect on magnetic GGA calculations
-a new GGA functional PBEsol is available which "restores the density-gradient expansion for exchange in solids and surfaces": use xctype=22
-F. Bultmark added a warning message for when metals run out of empty states
-Christian Meisenbichler has created a Git repository where you can compare different versions of the code. See the Wiki for details.
-added compensating background charge energy to total when chgexs≠0
-lots of improvements, optimisations and minor bug fixes

exciting-0.9.115-137
-internal releases only

exciting-0.9.114
-changed the Hartree-Fock routine (hopefully for the last time): use task=5 to run it, still an experimental feature
-added Hartree-Fock example
-fixed bug in spin-orbit coupling: affects the splitting of low-lying states
-many minor improvements, optimisations and fixes
-speed up of APW-local-orbital kinetic energy surface term thanks to Francesco Cricchio
-intraband Drude-like contribution to dielectric tensor now added to total when intraband=.true.
-added optics example for aluminium: Al-linopt
-upgraded to LAPACK 3.1.1 (still works fine with 3.0)
-EXCITING Wiki now up and running

exciting-0.9.94-113
-internal releases only

exciting-0.9.93
-fixed another symmetry problem in version 0.9.92 (thanks to user ravi-mse for pointing it out)
-added HfSiO4 example

exciting-0.9.92
-fixed serious bug in new 0.9.89 symmetry handling routine: affected magnetic calculations on some computers (thanks to everyone for pointing it out)
-regenerated species files with slightly finer radial mesh
-added exciting.bib file to source directory
-modified the LiF example

exciting-0.9.90/91
-internal releases only

exciting-0.9.89
-symmetry handling now greatly improved thanks to a very fruitful exchange visit by JKD and SS to the Uppsala group (Lars Nordström, Fredrik Bultmark, Francesco Cricchio and Sébastien Lebègue)
-all types of magnetic and non-magnetic cases now treated with all possible symmetries and k-point set reduction is maximised
-fixed bug in spin-spiral routine spotted by Francesco Cricchio who also improved the covering set for spherical harmonic transforms
-combined the EXCITING Users' and Developers' Guides into the EXCITING Manual and put the LaTeX source into main.f90
-changed the scissor correction usage back to pre-0.9.74 versions
-Sangeeta Sharma updated and tested optics and the magneto optical Kerr effect (MOKE)
-MOKE now uses task=122
-included MOKE example for Ni
-Sébastien Lebègue speeded up Brillouin zone integration by a factor of 2
-Sébastien Lebègue also added the Drude term to linear optics and (with SS) tested it against the Wien2k code
-renamed IAD.OUT to IADIST.OUT
-added more documentation to the code
-changed the anti-ferromagnetic example
-increased default vacuum to 10.0
-improved the species generation code
-included simple cubic Ununhexium as an example of how to make your own species files
-upgraded the internal BLAS and LAPACK libraries to version 3.1 (the code still works perfectly with version 3.0 though)
-the main code as well as Spacegroup now output both XCrySDen and V_Sim files for plotting the crystal structure
-lots of optimisations

exciting-0.9.75-88
-internal releases only

exciting-0.9.74
-IMPORTANT: the file EIGVEC.OUT has been replaced with collectively EVALFV.OUT, EVALSV.OUT, OCCSV.OUT, EVECFV.OUT and EVECSV.OUT: for tasks that require the eigenvectors/values rerun with the new version using task=1 and maxscl=1
-OEP-EXX faster by at least a factor of 2
-the Hartree-Fock routines have been considerably updated
-fixed spin-orbit coupling bug (may affect easy axis calculations)
-fixed problem in with rotation of spinor states (affects non-collinear OEP-EXX)
-fixed problem with the scissor correction in the linear optics code (discovered by Stephan Sagmeister)
-fixed bug in wavefunction and STM plotting
-fixed bug which affects the band-characters for non-collinear systems
-new variable bfinite: if .true. then the external magnetic fields are considered finite instead of infinitesimal, and their contribution is added to the total energy (.false. by default)
-external magnetic field energy now not included by default in the total energy
-force convergence now determined by the maximum rather than the average force
-MAFORCE.OUT replaced with FORCEMAX.OUT
-optimised geometry written to GEOMETRY_OPT.OUT
-new variable nwrite specifies after how many iterations STATE.OUT should be written (set to zero by default)
-increased the vacuum layer in the non-collinear chromium monolayer example (now gives the correct moment)
-changed default taufsm
-CPU time after every iteration now written to INFO.OUT
-many optimisations
-lots of simplifications
-minor bug fixes
Developer notes:
-arguments to zpotcoul have changed (see Developers' Guide)
-getevec and putevec have been replaced with subroutines for reading and writing eigenvalues, eigenvectors and occupancies separately: this is simpler and more efficient

Kay Dewhurst, Sangeeta Sharma, Claudia Ambrosch-Draxl, Lars Nordström, Clas Persson, Christian Brouder, Rickard Armiento, Andrew Chizmeshya, Per Anderson, Igor Nekrasov, Fredrik Bultmark, Frank Wagner, Fateh Kalarasse, Jürgen Spitaler, Stefano Pittalis, Nektarios Lathiotakis, Tobias Burnus, Stephan Sagmeister, Christian Meisenbichler, Francesco Cricchio, Sébastien Lebègue, Yigang Zhang, Fritz Körmann, Alexey Baranov