[Pw_forum] "STO Structure breaking - reg."

[Ari P Seitsonen]

Dear Muthu V,

   Still your system is cubic, is this what you want? After the relaxation 
of the cell there are off-diagonal components in the stress tensor; this 
might hint at a phase transition into a different kind of cell, but it has 
not occurred duering your relaxation. There are no symmetries in this 
system, is it correct or have you switched them off?

   The output says

      number of electrons       =        25.00

Thus there would be an spin-unpaired electron (or more, if the 
multiplicity is higher), but you do not treat the spin.

   I don't know the structure of this crystal, but you might check once 
more that what you want to calculate has the correct geometry.

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Institut für Chemie der Universität Zürich, CH-8057 Zürich
   Tel: +41 44 63 54 497  /  Mobile: +41 79 71 90 935


On Sun, 9 Mar 2014, Muthu V wrote:

> Dear All
> 
> i thank Ari P Seitsonen, xirainbow, Paolo Giannozzi for your kind reply.
> 
> i did same calculation with Ecut = 100Ry and 8x8x8 k-point mesh. but i got the same result as previous.so my convergence test seems to be correct.
> As Paolo mentioned i expanded 3 units in each direction i retrieved initial structure with all atoms. but i have one confusion.
> 
> Why i can't get initial structure with relaxed unit cell coordinates. ( one reason might be duo to symmetry breaking in HSTO compared to STO)
> 
> Attached is output file for vc-relax calculation with Ecut =100 and  K point mesh = 8x8x8
> 
> Thank you
> _________________________
> 
> Muthu.V 
> Project Fellow
> School of Physics
> 
> Madurai Kamaraj University , India
> 
> __________________________
> 
> 
>