[Pw_forum] ambiguous results with vc-relax

[Guda Karthik]

Hi,

    Here are the input and output files.

    b19_Acklatpos_new.* - original structure

    b19_pwscf.* - scf calculation with a structure obtained after vc-relax

    Please have a look if they are of help.

regards,
Karthik

On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi <giannozz at democritos.it>wrote:

>
> On Aug 4, 2010, at 4:41 , Guda Karthik wrote:
>
> > I am trying to relax an orthorhombic structure using vc-relax
> > (celldofree - xyz). I start with a structure which is at a Pressure
> > of -20.5 Kbar and at the end of the vc-relax I get a structure
> > which is at a pressure of -0.21 Kbar. Surprisingly, the structure
> > at pressure closer to zero is higher in energy than the original
> > structure by 8 * 10^-4 eV/formula unit. All the symmetry elements
> > have been conserved during relaxation and the initial and final
> > structures are the same. I am not able to make sense of this
> > result. I observe this inconsistency in my B2 structure as well.
> > Please help regarding this.
>
> hard to help without input and output
>
> P.
> ---
> Paolo Giannozzi, Dept of Physics, University of Udine
> via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
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>



-- 
Karthik Guda
Graduate Student
Materials Engineering
Purdue University
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