Elk version elk-8.3.15 released

Dear All,

Elk version 8.3.15 has just been released.

This version is considerably faster than previous versions, particularly for spin-polarised calculations. This is thanks to improvements in the second-variational step as well as in computing the density and magnetisation. Calculation of potential matrix elements (used for example in TDDFT and ultra long-range) have been made single-precision. This speeds up the calculations by nearly a factor of 2 without any noticeable loss in overall precision.

The meta-GGA code is now both faster and more reliable. It has also improved the predictions of the magnetic properties of materials with functionals such as SCAN. Thanks to Pietro Bonfa for all the testing.

The tensor moment code has been extensively re-written and simplified. The tensor moments are now exclusively 3-index and real. See the release notes and examples for details. Fixed tensor moment (FTM) calculations now work properly. Thanks to Leon Kerber for the analysis and testing.

Finally, the electron-phonon Bogoliubov code is now finalised but should still be considered as experimental. Thanks to Chung-Yu Wang for all the coding and careful testing.

Best wishes,
Kay Dewhurst, Sangeeta Sharma, Lars Nordström, Francesco Cricchio, Oscar Grånäs and Hardy Gross

---

elk-8.3.15
-considerable speed-up and optimisations throughout the entire code; spin-polarised calculations in particular are substantially faster
-greatly improved the meta-GGA calculations; these no longer require a large number of empty states for good convergence and consequently run much faster; removed the 'metagga' flag; thanks to Pietro Bonfa for the careful testing
-checked and highly optimised the TDDFT+U calculations
-removed the DFT+U scheme which interpolated between FLL and AFM
-rearranged the order of phonon line width plots to match that of the phonon dispersion plots
-further improved the electron-phonon Bogoliubov method; thanks to Chung-Yu Wang for the careful testing
-rewrote much of the tensor moment code; the tensor moments are now real and exclusively of the 3-index type; the corresponding matrices Gamma_t^kpr are now Hermitian and orthonormal; see the documentation of the routines 'tm2todm' and 'tm3todm' and references therein; thanks to Leon Kerber for the extensive testing
-writing out the old convention of complex 3-index tensor moments can be enabled with 'tm3old=.true.'
-Leon Kerber also found and fixed a problem with the fixed tensor moment (FTM) code
-the input block 'tmomfix' has been removed; use 'tm3fix' instead
-included a FTM example in elk/examples/FeGd-fixed-tensor-moment
-the RAM disk is now enabled by default; if problems are encountered with this then set 'ramdisk=.false.'
-included an example for calculating the dielectric function using time evolution; see elk/examples/TDDFT-time-evolution/Si-dielectric
-added more LaTeX documentation to the code
-many small improvements and minor bug fixes