[QE-developers] TR: Bugs in cp.x from QE 7.2 affecting stresses calculated with US pseudos and CG

[Paolo Giannozzi]

Thank you for reporting.

i) nkb and nhsa are actually the same variable. Not sure what "nrcx" is, 
but in any case, the called routine is in a module so one can just write
    real(dp) :: dbec(:,:,:,:)
and stop worrying about the correctness of the

ii) almost no code is executed for CG calculations (tcg=.true.) in 
from_scra.f90; for tcg=.false., the needed call is present, it seems to 
me. What did you change exactly?

iii) Is stress working after your changes? can you provide a simple example?

Paolo

On 04/10/2024 09:41, RABONE Jeremy wrote:
> 
> ------------------------------------------------------------------------
> *De :* RABONE Jeremy
> *Envoyé :* jeudi 3 octobre 2024 13:04
> *À :* users at lists.quantum-espresso.org
> *Objet :* Bugs in cp.x from QE 7.2 affecting stresses calculated with US 
> pseudos and CG
> 
> Hello,
> 
>    I have been getting some weird stress values in MD calculations using 
> cp.x from QE 7.2 with ultrasoft pseudopotentials and after some 
> rummaging I have found a couple of bugs:
> 
>      i) The dbec array gets inadvertantly altered through the call to 
> cg_sub.f90 where is is assigned a different size "real(dp) :: dbec(nkb, 
> nbspx, 3, 3)" than initially allocated in mainvar.f90 
> "ALLOCATE( dbec( nhsa, 2*nrcx, 3, 3 ), STAT=ierr )". The upshot of this 
> is that the values of dbec get jumbled and the resulting stress tensor 
> is messed up (and physically nonsensical). Also, since dbec is not 
> zeroed and the initially allocated size does not seem to correspond to 
> the used size, this also has the effect of introducing random values 
> into the stress tensor, although zeroing dbec after the allocation in 
> mainvar.f90 fixes this.
> 
>     ii) In fromscra.f90 the constraints contribution to the stress is 
> calculated "if ( tstress ) CALL nlfh( stress, bec_bgrp, dbec, lambda, 
> idesc )" before the dbec array has been calculated "if ( tstress ) CALL 
> caldbec_bgrp( eigr, cm_bgrp, dbec, idesc )".
> 
> 
> Kind regards,
> 
> Jeremy
> 
> 
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216