[Pw_forum] The total forces of TiO2(101) surface do not converge

[Giuseppe Mattioli]

Dear Andrey
I would be very surprised if your structure converged. :-)
I've opened your file with xcrysden and the slab seems anything but  
anatase (101).
Check the structure, first. Then

ecutwfc = 85,
ecutrho=850

It is not clear whether your PPs are norm conserving or ultrasoft  
ones. If they are NC, then you do not need to specify ecutrho, because  
it is automatically fixed at the ecutwfc*4 value. If they are US, then  
ecutwfc=85.0 is an extremely high cutoff for wavefunction, likely  
leading to a huge waste of time.

  cell_dofree = 'xy',

It is my opinion, but I suppose that when you want to simulate a  
surface with a slab, you should not optimize the xy lattice  
parameters, because in "real systems" they are generally kept fixed at  
the underlying bulk values.

HTH
Giuseppe

Quoting Andrey Chibisov <andreichibisov at yandex.ru>:

> Dear Colleagues.
> I am studing the TiO2(101) surface. But during the structure relaxation the
> total energy do not converge.
> I attach the input file.
>
>  
> -- 
> Best regards,
> Andrey Chibisov. Ph.D.
> Numerical method of mathematical physics Laboratory,
> Computational Center, Russian Academy of Sciences.
> Khabarovsk, Russia
> Web page: https://www.researchgate.net/profile/A_Chibisov
> http://ru.linkedin.com/pub/andrey-chibisov/55/253/986/en
>  


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    Giuseppe Mattioli
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