[Pw_forum] about the from scale_h : error

[Lorenzo Paulatto]

On Wed, 03 Mar 2010 12:30:32 +0100, Wei Zhou <zdw2000 at gmail.com> wrote:
>> the initial structure is get from the VASP soft,and is consist with the
>> experiment at 500kba,

Dear Wei,
I think you may have done a unit of measure mistake while converting the  
system parameters from VASP to QE. In order to get the huge pressure you  
are requiring the cell parameter has to shrink by a factor ~ 0.57 (i.e not  
too far away from the bohr/Angstrom conversion). Furthermore, you smearing  
degauss is probably too high (remember it is expressed in Rydberg) and you  
cutoff energy is probably unnecessarily high (the pseudopotential you are  
using is well converged at much lower ecutwfc and ecutrho).

> I wonder if the two Ba pseudo potential of pwscf web cannot  work at   
> high pressre..........

It is possible: when the atoms get very close to each other you need  
harder pseudopotentials; however that's not the cause of your problem, I  
would bet on the smearing instead.

regards

-- 
Lorenzo Paulatto

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