[QE-users] nscf in super cell

[Fariba Islam]

Thanks

On Tue, May 12, 2020 at 12:41 PM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> On Tue, May 12, 2020 at 7:08 AM Fariba Islam <ezqhaz at gmail.com> wrote:
>
>> I wrote the following code for nscf calculation of a silicon supercell.
>> Why do I get
>>
> "c_bands:  2 eigenvalues not converged
>>  c_bands:  1 eigenvalues not converged...." in my output file and the
>> calculation is not stopping
>>
>
> if it is not stopping, there is no problem. In a scf calculation, the
> iterative diagonalization starts from wavefunctions computed at the
> previous scf step and usually converges quickly. The maximum number of
> internal iterations is thus small (20 if I remember correctly). In a
> non-scf calculation, there isn't such a good starting point and iterative
> diagonalization sometimes does not converge for all eigenvalues in 20
> iterations, but it is usually sufficient to repeat the diagonalization.
>
> Paolo
>
> &control
>>     calculation = 'nscf'
>>     restart_mode='from_scratch'
>>     prefix = 'si_b'
>>     outdir='./tmp/'
>>     pseudo_dir='../pseudo/'
>> /
>> &system
>>     ibrav=2, celldm(1) = 20.8218,
>>     nat=16, ntyp=1,
>>     ecutwfc=40
>>     ecutrho=160
>>     noinv=.true.
>>     nosym=.true.
>>     occupations='smearing' , smearing='gaussian',degauss=0.005
>> /
>> &electrons
>>     conv_thr=1e-8
>> /
>> ATOMIC_SPECIES
>>  Si  28.0855  Si_ONCV_PBE-1.0.upf
>>
>> ATOMIC_POSITIONS (alat)
>> Si 0.000000   0.000000   0.000000
>> Si -0.374989   0.375011   0.375011
>> Si -0.250000   0.250000   0.000000
>> Si -0.624989   0.625011   0.375011
>> Si 0.000000   0.250000   0.250000
>> Si -0.374989   0.625011   0.625011
>> Si -0.250000   0.500000   0.250000
>> Si -0.624989   0.875011   0.625011
>> Si -0.250000   0.000000   0.250000
>> Si -0.624989   0.375011   0.625011
>> Si -0.500000   0.250000   0.250000
>> Si -0.874989   0.625011   0.625011
>> Si -0.250000   0.250000   0.500000
>> Si -0.624989   0.625011   0.875011
>> Si -0.500000   0.500000   0.500000
>> Si -0.874989   0.875011   0.875011
>>
>> K_POINTS {automatic}
>> 12 12 12 0 0 0
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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
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
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