from readmat : error # 1 wrong qpoint

[dinesh169]

Hello Everyone,

I am using EPW_v2.3.5. I am trying to calculate electron self-energy. I have successfully done it for bulk silicon and graphene. Now I am trying for Mos2, I am facing the following error

from readmat : error # 1
wrong qpoint

which means mismatch of q-points between the epw.in and prfix.dyn_q files. But I checked this is not the case in my calculations. Below is the epw input file

--
&inputepw
prefix = 'mos2'
amass(1) = 32.065,
amass(2) = 95.94,
outdir = '../epw_output/'

iverbosity = 0

elph = .true.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

nbndsub = 9
nbndskip = 0
kmaps = .false.



wannierize = .true.
num_iter = 5000
iprint = 2
dis_win_max = 30
dis_froz_max= 2.5
proj(1) = 'random'

elinterp = .true.
phinterp = .true.

tshuffle2 = .true.
tphases = .false.
epstrict = .true.

elecselfen = .true.
phonselfen = .false.
a2f = .false.
fly = .true.
parallel_k = .true.
parallel_q = .false.
ephwrite = .true.
fsthick = 8.d10

degaussw = 0.025

filukk = './mos2.ukk'
dvscf_dir = './save'
max_memlt = 5.0d0
nkf1 = 10
nkf2 = 10
nkf3 = 1
nqf1 = 10
nqf2 = 10
nqf3 = 1

nk1 = 16
nk2 = 16
nk3 = 1

nq1 = 8
nq2 = 8
nq3 = 1
/
10 cartesian
0.0000000 0.0000000 0.0000000 0.0312500
0.0000000 0.1461865 0.0000000 0.1875000
0.0000000 0.2923730 0.0000000 0.1875000
0.0000000 0.4385595 0.0000000 0.1875000
0.0000000 -0.5847460 0.0000000 0.0937500
0.1266012 0.2192798 0.0000000 0.1875000
0.1266012 0.3654663 0.0000000 0.3750000
0.1266012 0.5116528 0.0000000 0.3750000
0.2532025 0.4385595 0.0000000 0.1875000
0.2532025 0.5847460 0.0000000 0.1875000

I can interpolate the phonon band structure using "q2r.x and matdyn.x" binaries. I dont know why epw complain about the q-point.

And one thing I noticed in this case is that code does not say anything about reading q-points in star. I mean
===================================================================
irreducible q point # 2
===================================================================


q( 2 ) = ( 0.0000000 0.1461865 0.0000000 )


===================================================================
irreducible q point # 3
===================================================================

The 2nd q-point has further 6 q-points in star.
Is this problem related with the symmetry in the system?

Many thanks in advace.

[sponce]

Dear dinesh169,

Can you use the latest EPW v4 as we do not really support such old version.

The installation is very easy. You can follow the steps http://epw.org.uk/Main/DownloadAndInstall

Bugs related to symmetry have been fixed in this new version.

Note however that the version 6 of QE and version v4.1 of EPW will be available very soon (first week of October if everything goes well).

Best,

Samuel

[dinesh169]

Hello Dr. Samuel Ponc,

Thank you very much for your reply. I am using the new EPW 4.0, and the problem mentioned previously is solved.
Now I am trying the same calculations for bulk MoS2. I came across this error:

Error in routine calbec (3):
size mismatch

I am using the uniform k-grid for wannierization. I read in the forum that it may be because of GGA functional and i am also using the same.
Is there any way to avoid it? because i would not be good if I have to change the functional, then i might have to run all the for the single layer.

Below is the nscf and epw files respectively:
&CONTROL
calculation = 'nscf' ,
restart_mode ='from_scratch' ,
outdir = './' ,
pseudo_dir = './' ,
prefix = 'mos2' ,
wf_collect=.false.
nstep= 80
etot_conv_thr = 1.0D-7
forc_conv_thr = 1.0D-5
tstress = .true.
tprnfor = .true.
verbosity = 'high'

/
&SYSTEM
ibrav = 0,
A = 3.16
nat = 6,
ntyp = 2,
ecutwfc = 70 ,
ecutrho = 300 ,
occupations = 'smearing' ,
degauss = 0.03 ,
smearing = 'mp'
nbnd = 30
/
&ELECTRONS
electron_maxstep = 100
conv_thr = 1.0d-10
mixing_mode = 'plain'
mixing_beta = 0.5
mixing_ndim = 8
diagonalization = 'david'
diago_david_ndim = 4
diago_full_acc = .true.
/
&IONS
ion_dynamics = 'bfgs'
trust_radius_max = 0.5
trust_radius_min = 1.0D-16
/
&CELL
cell_dynamics = 'bfgs'
press = 0.00D0
cell_dofree = 'all'
cell_factor = 1.8D0
/
ATOMIC_SPECIES
S 32.065 16-S.GGA.txt.UPF
Mo 95.94 42-Mo.GGA.txt.UPF

CELL_PARAMETERS (alat)
0.999060846 0.000000000 0.000000000
-0.499530423 0.865212072 -0.000000000
0.000000000 0.000000000 3.840581648

ATOMIC_POSITIONS (crystal)
Mo 0.333333000 0.666667000 0.249999899
Mo 0.666667000 0.333333000 0.750000101
S 0.333333000 0.666667000 0.619509115
S 0.666667000 0.333333000 0.380490885
S 0.666667000 0.333333000 0.119509061
S 0.333333000 0.666667000 0.880490939

K_POINTS crystal
144
0.00000000 0.00000000 0.00000000 6.944444e-03
0.00000000 0.00000000 0.25000000 6.944444e-03



--
&inputepw
prefix = 'mos2'
amass(1) = 32.065,
amass(2) = 95.94,
outdir = './'



iverbosity = 0

elph = .true.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

nbndsub = 30
nbndskip = 0

wannierize = .true.
num_iter = 10000
iprint = 2
dis_win_max = 15
dis_froz_max= 5
proj(1) = 'random'
kmaps = .false.

elinterp = .true.
phinterp = .true.

tshuffle2 = .true.
tphases = .false.

elecselfen = .true.
phonselfen = .false.
a2f = .false.

parallel_k = .true.
parallel_q = .false.

fsthick = 136056981 ! eV
eptemp = 300 ! K (same as PRB 76, 165108)
degaussw = 0.1 ! eV

dvscf_dir = './save'
filukk = './mos2.ukk'

nkf1 = 12
nkf2 = 12
nkf3 = 4
nqf1 = 6
nqf2 = 6
nqf3 = 2

nk1 = 6
nk2 = 6
nk3 = 2

nq1 = 6
nq2 = 6
nq3 = 2
/
14 cartesian
0.0000000 0.0000000 0.0000000 0.0277778
0.0000000 0.0000000 -0.1301886 0.0277778
0.0000000 0.1926310 0.0000000 0.1666667
0.0000000 0.1926310 -0.1301886 0.1666667
0.0000000 0.3852620 0.0000000 0.1666667

Have a nice evening.

[carla.verdi]

Dear Dinesh

Unfortunately the error seems related to the pseudo. It looks like EPW experiences problems when using GGA in some cases - I have personally used PBE for some system and it was working fine. We need to investigate this further - if you want, it could be useful if you send us the pseudo so to reproduce the problem.

Best
Carla

[dinesh169]

Hello Carla,

Thank you very much for your reply. Here is the link to pseudopotential files

ftp://ftp.abinit.org/pub/abinitio/Psps/GGA_FHI/42-Mo.GGA.fhi

I converted this file to UPF for using in quantum espresso.
Actually I solved the problem. I was using ecutrho = 4*ecutwfc+X(X= some integer). When i specified ecutrho =4*ecutwfc default value, it worked out. It was just an intuitive guess. In the source code this error was because of size mismatch between betapsi and number of k-points, number of bands. So I tried default values and It worked out.

Have a nice day.
Dinesh

[carla.verdi]

That's great to know Dinesh!
I think it's best to always keep ecutrho at the default 4*ecutwfc for NC pseudos with QE.

Best
Carla

[sponce]

Dear Dinesh,

Thanks for letting us know. Happy that it now works for you.

Best,

Samuel

[dinesh169]

Dear Admins,

Thank you very much for your replies. I want to ask you one question.
Phonon calculations are also very time consuming. I tried to do phonon calculation on every q point separately and then put the prefix.dyn_q#, prefix.dvscf_q# and patterns.#.xml ( in prefix.phsave directory) together in save directory. I face the the following error

Error in routine read_modes (1):
problems with current_iq

Though when I do the phonon calculations on a grid at one time and copy the dyn, dvscf, patterns ( in prefix.phsave directory) then everything works fine. Am I missing some files or is this not the right way to do it?

have a nice evening.

Best wishes,

[carla.verdi]

Dear Dinesh

The procedure is correct as long as you are copying every file correctly - please double check again, you should not encounter any problem.

Best
Carla

[roxana]

Hi,

If I remember correctly when you calculate each q-point separately you may need to change the q-point number in the patterns.*.xml files. At the beginning of each file you have the following lines.

<?iotk binary="F"?>
<?iotk qe_syntax="F"?>
<Root>
<IRREPS_INFO>
<QPOINT_NUMBER type="integer" size="1">
2

The line after QPOINT_NUMBER should be the nr of the respective q-point. In other words, 2 if this is q-point nr 2. This number will be the correct value if you calculated all q-points at once on a mesh, otherwise it will be 1.

Best,
Roxana