EPW Forum

Hello, Can you make sure that you are providing the correct list of q-points to EPW. It should be the same as the one of the ouptut of the phonon calculation. It should look like: Dynamical matrices for ( 3, 3, 3) uniform grid of q-points ( 4q-points): N xq(1) xq(2) xq(3) 1 0.000000000 0.000000000 0...

Dear eliephys78, Could you give us the list of q-points (the 28 ones) that is reported in the ph.out file. Then make sure that the list of q-point that you provide in the epw.in file is exactly the same. Note that 1.0 0.0 0.0 is different from -1.0 0.0 0.0 even in crystal coordinate. This is because...

Dear Diego, The EPW code rely on density functional perturbation theory (DFPT). The electron-phonon matrix elements are computed within that framework in QE. Such theory implies that the system is at equilibrium. Soft phonons indicates that the system is not at equilibrium. Since the theory is ill d...

Dear Nandan, EPW only supports k/q-point parallelization. EPW also needs/reads the ground-state wavefunction (produced with the nscf run). Therefore it should look like: mpiexec -np 64 ~/source/espresso-5.4.0/bin/pw.x -npool 8 < scf.in > scf.out 2>&1 & mpiexec -np 64 ~/source/espresso-5.4.0/...

Dear Nandan,

It look like the error has to do with not being able to write on disk.

Maybe a disk quota exceeded?

Maybe try not to write in a /tmp directory.

Sam

Dear eliephys78, You should have the same ph and nscf grid. If you want to do a 15x15x15 scf+nscf calculations, you should then do a 15x15x15 q-point ph.x grid. You should therefore have 216 cartesian ... in your epw input file. I would however keep the 28 (maybe a 6x6x6 q-grid? ) and do a 15x15x15 ...

Dear eliephys78, eptemp is the temperature at which you want your results. The temperature eptemp will give the value of the Bose-Einstein n(T) factors. degaussw is the broadening on the delta of electron properties. degaussq is the broadening on the delta of phonon properties. If those parameters a...

Dear Vahid, QE should print a dvscf file for each q-point. Those are binary files so you should not be able to see their content but they should have non-zero size. The pp.py script do not copy the same file over. All the files should be different for each q-points. You should also have one .dyn fil...

Dear Alaska,

Happy to hear that you could solve you problem.

is indeed the way to reduce the RAM usage.

Best,

Samuel

Dear Vahid,

This is because you have specified in your input file.

Could you format your posts using the "code" balist please.

Best,

Samuel