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

[Paolo Giannozzi]

It seems to me that the check leading to the error message is not correct
for LSDA: the number of bands must be sufficient to accommodate up- or
down-spin electrons, not all of them

Paol

On Tue, Mar 31, 2020 at 9:52 AM <mkondrin at hppi.troitsk.ru> wrote:

> 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
> /
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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