[QE-users] TB09, TPSS

[Michal Krompiec]

Dear Paolo,
I changed io_rho_xml.f90 so that if the kinetic energy density file
isn't found, the array is set to 0:

155d144
<       LOGICAL :: ekin_density_exists
172,180c161,164
<          INQUIRE( FILE=TRIM(dirname) // "ekin-density",
EXIST=ekin_density_exists)
<          IF ( ekin_density_exists ) THEN
<            CALL read_rhog( TRIM(dirname) // "ekin-density", &
<              root_bgrp, intra_bgrp_comm, &
<              ig_l2g, nspin_, rho%kin_g, gamma_only )
<            WRITE(stdout,'(5x,"Reading meta-gga kinetic term")')
<          ELSE
<            rho%kin_g = 1.0
<          ENDIF

Now I can start a TB09 calculation from a PBE density, but still my
test case diverges immediately (=faster than when starting from
scratch), regardless of diagonalization method. For example:
     The initial density is read from file :
     ./sic.save/charge-density

     Starting wfcs from file

     total cpu time spent up to now is        0.3 secs

     Self-consistent Calculation

     iteration #  1     ecut=    82.00 Ry     beta= 0.40
     CG style diagonalization


 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     Error in routine c_bands (1):
     too many bands are not converged
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

I would be very grateful for any suggestions.
Best,
Michal

P.S. This is my input file:
&CONTROL
    calculation  = "scf"
    prefix       = "sic"
/

&SYSTEM
    a           =  4.34800e+00
    ibrav       = 1
   ecutwfc          = 82
   ecutrho          = 328
    nat         = 8
    ntyp        = 2
    occupations = "fixed"
input_dft='tb09'
/
&ELECTRONS
   electron_maxstep = 1000
   conv_thr         = 1e-10
   mixing_mode      = 'plain'
   mixing_beta      = 0.4
  startingpot = 'file'
  startingwfc = 'file'
  diagonalization = 'cg'
/

K_POINTS automatic
8 8 8   1 1 1

ATOMIC_SPECIES
Si     28.08500  Si.upf
C      12.01060  C.upf


ATOMIC_POSITIONS {angstrom}
Si      0.000000   0.000000   0.000000
Si      0.000000   2.174000   2.174000
Si      2.174000   0.000000   2.174000
Si      2.174000   2.174000   0.000000
C       1.087000   1.087000   1.087000
C       1.087000   3.261000   3.261000
C       3.261000   1.087000   3.261000
C       3.261000   3.261000   1.087000

On Fri, 8 May 2020 at 09:39, Paolo Giannozzi <p.giannozzi at gmail.com> wrote:
>
> On Thu, May 7, 2020 at 10:33 PM Michal Krompiec <michal.krompiec at gmail.com> wrote:
>
>>
>>  it was suggested to start from a density calculated with a different functional, but when I try to read in PBE density, it complains that it cannot read the kinetic energy file (which obviously cannot be there).
>
>
> this can be easily changed, I think: just disable the check and set the kinetic energy density to zero
>
>>
>> Should TPSS or SCAN pseudos work better (and where do I get them from)?
>
>
> I don't think the problem is in the pseudos but in the nasty numerical behavior of meta-GGAs. See for instance here: https://gitlab.com/QEF/q-e/-/issues/32. Note that several bugs have been fixed in the development version.
>
> Paolo
>
>> Thanks,
>> Michal Krompiec
>> Merck KGaA
>>
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
>> users mailing list users at lists.quantum-espresso.org
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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)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users