[QE-users] epsilon.x with nspin=2 and "bad bands number"

[mkondrin at hppi.troitsk.ru]

Dear QE Developers and Users!

When launching epsilon.x after scf run with nspin=2 I have got an error 
"bad bands number" although the same calculations for spin unpolarized 
calculations completes OK. My QE version is 6.4. The example input files 
are below.

I have found that increasing nbnd parameter to twice as large number (that 
is nbnd=240 in the example below) aloows one to avoid this error. So I 
simply commented out the check of bands number in the epsilon.x code. This 
also solves my problem.

Sincerely yours,
M. Kondrin

#scf.in
&control
title='GeV3H2 TDDFT props',
calculation='scf',
prefix='gev3h2',
disk_io='low',
pseudo_dir = '../../../../QE/pseudo',
outdir='./tmp'
/
&SYSTEM
  ibrav = 0
  A =    7.56616
  nat = 53
  ntyp = 3
tot_charge=-2,
ecutwfc=70,
nspin=2,
tot_magnetization=0,
occupations='fixed',
nbnd=120
/
&electrons
    mixing_beta = 0.7,
    conv_thr =  1.0d-6
/
&ions
/
&cell
/
ATOMIC_SPECIES
Ge      73.     Ge.pbe-mt_fhi.UPF
C       12.     C.pbe-mt_fhi.UPF
H       1.01    H.pbe-mt_fhi.UPF

K_POINTS {Gamma}

CELL_PARAMETERS (alat= 14.29797028)
   1.017268700   0.000966298  -0.001276172
   0.509471188   0.880497388  -0.001276172
   0.507868198   0.293217841   0.838703908

ATOMIC_POSITIONS (crystal)
Ge       0.030176730   0.053156603   0.041666667
C        0.339908341  -0.004633174  -0.011768993
C        0.660599947  -0.006910063  -0.006729167
C       -0.000457701   0.001992166   0.668790467
C        0.663957422  -0.007183033   0.353505398
C        0.002429970   0.661897060   0.336749457
C        0.333251116   0.667546805   0.332866839
C        0.666870377   0.667773394   0.332963326
C        0.335418462   0.331461365   0.000834511
C        0.663274875   0.354933130  -0.007069496
C        0.333102298  -0.001079778   0.330162200
C        0.002942686   0.661030547   0.670114003
C        0.004630479   0.338493709   0.657033452
C        0.331879118   0.332848285   0.666332211
C        0.665920813   0.333088498   0.667953085
C       -0.013745535  -0.003011939   0.348514247
C        0.332436215   0.002337467   0.663352392
C        0.334816038   0.662930722   0.002745506
C        0.675328893   0.659398752   0.001209447
C        0.666876571  -0.000038910   0.667481514
C        0.002724484   0.670973412   0.004393570
C        0.333135665   0.666691617   0.667510819
C        0.667302097   0.666041411   0.667309037
C        0.001571177   0.334667054   0.333270037
C        0.336541956   0.330626528   0.331882294
C        0.665918954   0.332907549   0.332005117
C        0.412359921   0.080608849   0.078939763
C        0.086345273   0.097078869   0.734819086
C        0.744839624   0.078702855   0.426299882
C        0.080995867   0.750897118   0.419980941
C        0.416641716   0.750197668   0.415822514
C        0.750485049   0.751454216   0.417001122
C        0.090243396   0.422733386   0.090062500
C        0.423934581   0.408004440   0.082123887
C        0.728400204   0.420058458   0.090402830
C        0.422302786   0.080390647   0.413219331
C        0.084413111   0.750231035   0.753171133
C        0.090516367   0.419375912   0.729827935
C        0.415559939   0.416462956   0.750370007
C        0.750425784   0.417414379   0.751328216
C        0.081341168   0.083791035   0.414542867
C        0.421436273   0.080903363   0.746583877
C        0.420402612   0.748517295   0.080587828
C        0.751871968   0.747914872   0.082498823
C        0.748666279   0.081762157   0.750063296
C        0.087966508   0.743424992   0.095102326
C        0.415786528   0.750082218   0.750466495
C        0.752706805   0.746791377   0.751451039
C        0.083372243   0.416456762   0.415851819
C        0.417291922   0.416031236   0.416024296
C        0.750244835   0.417412520   0.415380248
H        0.031525882   0.371888089   0.028431477
H        0.711445245   0.051807451   0.054901857

#epsilon.in
&inputpp
	calculation = 'eps'
	prefix='gev3h2',
	outdir='./tmp'
/
&energy_grid
	smeartype='gaussian'
	intersmear=0.1
	wmin=0.0
	wmax=15.0
	nw=1000
/