[Pw_forum] Question on epsilon.x

[Andrea Ferretti]

  Dear Mohsen,

  according to the error you get (try always to locate it into the sources)

>      from epsilon : error #         1
>      bad band number

  your problem is that you didn't compute any empty state.
  silicon has a gap, you are working with fixed occupations (no smearing, which
  is the standard choice here), but you are also not specifying the number of
  bands to be computed, so the code computes just the valence.

  Note also that during a scf calculation, unoccupied bands are computed with a
  lowered accuracy. Use diago_full_acc = .TRUE.  to lift this
  optimization and use the full accuracy.
  (this is not the case of nscf or bands calculations,
  where diago_full_acc = .TRUE. is the default)

  Anyway, I would run are the following calculations instead:

  * scf,     only valence bands, just compute the charge density
  * nscf,    compute a certain number of empty states as well
            (to be checked as a convergence parameter on the epsilon
            results)
  * epsilon

  hope it helps
  Andrea


>> Dear Andrea thanks for your answers, they were helpful for me.
>> I faced with a new question, can any one help me, please?:
>> I run a PW.X with this input file
>>  &control
>>     calculation = 'scf'
>>     restart_mode='from_scratch',
>>     prefix='silicon',
>>     tstress = .true.
>>     tprnfor = .true.
>>     pseudo_dir = '/home/nano/Desktop/esp/psudo'
>>     outdir='/home/nano/Desktop/esp/out/si'
>>  /
>>  &system   
>>     ibrav=  2, celldm(1) =10.20, nat=  2, ntyp= 1,
>>     ecutwfc =70.0,
>>  /
>>  &electrons
>>     mixing_mode = 'plain'
>>     mixing_beta = 0.7
>>     conv_thr =  1.0d-8
>>  /
>> ATOMIC_SPECIES
>>  Si  28.086  Si.pz-vbc.UPF
>> ATOMIC_POSITIONS
>>  Si 0.00 0.00 0.00
>>  Si 0.25 0.25 0.25
>> K_POINTS
>>    10
>>     0.1250000  0.1250000  0.1250000   1.00
>>     0.1250000  0.1250000  0.3750000   3.00
>>     0.1250000  0.1250000  0.6250000   3.00
>>     0.1250000  0.1250000  0.8750000   3.00
>>     0.1250000  0.3750000  0.3750000   3.00
>>     0.1250000  0.3750000  0.6250000   6.00
>>     0.1250000  0.3750000  0.8750000   6.00
>>     0.1250000  0.6250000  0.6250000   3.00
>>     0.3750000  0.3750000  0.3750000   1.00
>>     0.3750000  0.3750000  0.6250000   3.00
>> Every things done well, But when i run epsilon.x with this input file:
>> &inputpp
>>     outdir= '/home/nano/Desktop/esp/out/si'
>>    prefix='silicon',
>>    calculation= 'eps',
>>  /
>>  &energy_grid
>>     smeartype='gauss'
>>     intersmear=0.1
>>     intrasmear=0.1
>>     wmax=30.0d0
>>     wmin=0.0d0
>>     nw=100
>>     shift=0.0d0
>>  /
>> 
>> I get this eror:
>>   Program POST-PROC v.4.1.2  starts ...
>>      Today is 24May2010 at 15:22:14
>> 
>>      Parallel version (MPI)
>> 
>>      Number of processors in use:       1
>> 
>> 
>>      Reading input file...
>>      Broadcasting variables...
>>      Reading PW restart file...
>> 
>>      Planes per process (thick) : nr3 = 40 npp =  40 ncplane = 1600
>> 
>>      Proc/  planes cols     G    planes cols    G      columns  G
>>      Pool       (dense grid)       (smooth grid)      (wavefct grid)
>>         1    40   1003    20875   40   1003    20875    295     3215
>> 
>> 
>> 
>>      Fermi energy [eV] is:  5.93574
>>      The system is a dielectric...
>> 
>>      Performing eps calculation...
>> 
>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>      from epsilon : error #         1
>>      bad band number
>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>> 
>>      stopping ...
>> 
>> and in the command prompt it print: "application called 
>> MPI_Abort(MPI_COMM_WORLD, 0) - process 0"
>> Where is the problem?
>> Thanks for your reply.
>> Mohsen Modaresi
>>  
>>

-- 
Andrea Ferretti
Oxford University, Department of Materials
Parks Road, Oxford OX1 3PH, UK
Tel: +44 (0)1865 612796;  Skype: andrea_ferretti
URL: http://quasiamore.mit.edu

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