EPW Forum

Dear Developers,

I am trying to run EPW on my 2D system. But after doing phonon and all steps, in the epw step error appeared. The error is given below;

Calculating kgmap

Progress kgmap: ########################################
kmaps : 0.37s CPU 1.15s WALL ( 1 calls)
Symmetries of Bravais lattice: 24
Symmetries of crystal: 12


===================================================================
irreducible q point # 1
===================================================================

Symmetries of small group of q: 12
in addition sym. q -> -q+G:

Number of q in the star = 1
List of q in the star:
1 0.000000000 0.000000000 0.000000000
Imposing acoustic sum rule on the dynamical matrix

q( 1 ) = ( 0.0000000 0.0000000 0.0000000 )

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine readdvscf (80):
../0p_ph1/save/Sb0p.dvscf_q1 too short, check ecut
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


However, this error I have also seen discussed in some queries. But I am unable to understand the solution.
Kindly tell me the solution.

Thank You

Regards
Sumit Kukreti
IIT JODHPUR INDIA

Hi Sumit,

It looks like you have used a larger "ecut" value in scf.in (and also in nscf.in) during your EPW calculation than that you have used in your scf.in during the phonon calculation, could your double check?

The EPW code expects consistency in some of these input parameters used during the phonon calculation.

Best,
Hari Paudyal

Thank You, sir,

Yes, with the said correction, the error resolved, but on moving forward, the calculation again stuck with giving one more error;

Using uniform q-mesh: 50 50 1
Size of q point mesh for interpolation: 2500
Using uniform MP k-mesh: 50 50 1
Size of k point mesh for interpolation: 468
Max number of k points per pool: 8

Fermi energy coarse grid = -3.155303 eV

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine efermig (1):
internal error, cannot bracket Ef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

stopping ...


Give me some suggestions to resolve this also.

Thank You

Regards
Sumit Kukreti
IIT Jodhpur INDIA

Hi Sumit,

Can you confirm your wannier bands (prefix_bands.dat) are on top of DFT bands?

Best,
Hari