[QE-users] issue with fixed ibrva vc-relax calculation

[rekha sharma]

A gentle reminder.

Thank you.


On Sat, Oct 31, 2020 at 12:34 PM rekha sharma <rekha1997jpr at gmail.com>
wrote:

> Dear Users
>
> I have been doing a vc-relax calculation of a binary compound with AB2
> structure that is occupying a triclinic space group with ibrav=14.
> I used QE version 6.5.
>
> To keep the ibrav 14 from in the final vc-relax structure,  I performed
> the vc-relax with celld_dofree='ibrav'
> Job has been finished without any warning or error. The final geometry is
> mentioned in appendix-A in below to this query.
>
> If I choose the CELL_PARAMETERS and ATOMIC_POSITIONS from above output and
> update the case.in file then it gives me ibrav= -13.
>
> I am wondering whether I can choose celldm(1) to celldm(6) and
> ATOMIC_POSITIONS from the appendix-A?
>
> Are these celldm's final relaxed cell_parameters?
>
> Please guide me for the above two queries.
>
> Thank you very much
>
> Regards
> Rekha
>
>
>              Appendix-A
>
>
> ibrav =     14
>  celldm(1) =      7.46334414
>  celldm(2) =      0.99999702
>  celldm(3) =      1.79237850
>  celldm(4) =      0.11014359
>  celldm(5) =      0.10863152
>  celldm(6) =      0.24294684
> Input lattice vectors:
>      1.00112336     0.00000000     0.00000000
>      0.24321903     0.97112641     0.00000000
>      0.19492754     0.15492538     1.77703235
> New lattice vectors in INITIAL alat:
>      1.00112336     0.00000000     0.00000000
>      0.24321903     0.97112641     0.00000000
>      0.19492754     0.15492538     1.77703235
> New lattice vectors in NEW alat (for information only):
>      1.00000000     0.00000000     0.00000000
>      0.24294611     0.97003671     0.00000000
>      0.19470881     0.15475153     1.77503835
> Discrepancy in bohr =     0.000000    0.000000    0.000000
>
>      bfgs converged in   4 scf cycles and   3 bfgs steps
>      (criteria: energy <  1.0E-04 Ry, force <  1.0E-03Ry/Bohr, cell <
>  5.0E-01kbar)
>
>      End of BFGS Geometry Optimization
>
>      Final enthalpy =     -68.4522400954 Ry
> Begin final coordinates
>      new unit-cell volume =    715.80761 a.u.^3 (   106.07174 Ang^3 )
>      density =      4.43480 g/cm^3
>
> CELL_PARAMETERS (alat=  7.45496956)
>    1.001123355   0.000000000   0.000000000
>    0.243219029   0.971126408   0.000000000
>    0.194927536   0.154925376   1.777032345
>
> ATOMIC_POSITIONS (crystal)
> A            0.0000235084       -0.0000109097        0.0000009223
> B            0.9616465677        0.4631487680        0.2331366069
> B            0.5360299239        0.0391621417        0.7668624708
> End final coordinates
>
>
>                                                            Appendix- B
>
>
> &CONTROL
>   calculation='vc-relax',
>   outdir='./tmp',
>   prefix='scf',
>   pseudo_dir='.',
>   verbosity='low',
> etot_conv_thr = 0.0001
> forc_conv_thr = 0.001
>     nstep = 400
>   tstress = .true.
>   tprnfor = .true.
>
> /
>
> &SYSTEM
>   ibrav=14,
>   celldm(1)=7.4549695614d0, celldm(2)=1.0000000000d0,
> celldm(3)=1.7936628644d0,
>   celldm(4)=0.1100812622d0, celldm(5)=0.1085198771d0,
> celldm(6)=0.2422605780d0,
>   nat=3,
>   ntyp=2,
>   ecutwfc=50,
>   ecutrho=500,
>
> /
>
> &ELECTRONS
>   conv_thr=1d-010,
>   mixing_beta=0.3d0,
> /
> &IONS
> /
> &CELL
> cell_dofree='ibrav'
> /
>
> ATOMIC_SPECIES
>    A  A.pbe-n-rrkjus_psl.1.0.0.UPF
>    B  B.pbe-n-rrkjus_psl.1.0.0.UPF
>
> ATOMIC_POSITIONS {crystal}
>   A   0.0000000000d0   0.0000000000d0   0.0000000000d0
>   B   0.9617000000d0   0.4632000000d0   0.2330000000d0
>   B   0.5360000000d0   0.0391000000d0   0.7670000000d0
>
> K_POINTS {automatic}
>   11 11 5 0 0 0
>
> --
>
>
>
>
>
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