[Pw_forum] ambiguous results with vc-relax

Paolo Giannozzi giannozz at democritos.it
Sat Aug 14 12:27:46 CEST 2010

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

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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