[Pw_forum] converge problem in calculating the vacancy on TiO2 surfaces

[vega lew]

Dear APSI

thank you for you suggestions to me.

I will try it ASAP.

vega

On Sun, Mar 1, 2009 at 5:08 PM, Ari Paavo Seitsonen
<ari.p.seitsonen at iki.fi>wrote:

>
> Dear Vega,
>
>  Just my guesses and suggestions: One could try mixing of the density, like
>
>  &electrons
>    mixing_beta   = 0.7
>  /
>
> (or a value even smaller than 0.7, or some other parametres for the mixing)
> since with a defect you might now have defect levels in the band gap,
> leading to a more difficult a convergence. Eventually one could also switch
> on the broadening of the occupation numbers, eventually switching it off for
> the physical/production jobs, but just to check if the problem in
> convergence comes due to this.
>
>  And in the original paper the authors discuss spin-polarisation, one might
> test also this (nspin = 2), with different initial magnetisations
> [starting_magnetization(xx) = ...] for the atoms surrounding the defect.
>
>    Greetings,
>
>       apsi
>
>
> On Sun, 1 Mar 2009, vega lew wrote:
>
>  Dear all,
>>
>> I am planning to calculate the Oxygen vacancy properties of TiO2 surfaces.
>> The calculation for the ideal surfaces are quite normal and the results
>> are
>> in line with the one that literature reported.  But, when I tried to
>> calculate the anatase 101 surface with an Oxygen vacancy (O2c was removed
>> directly from the stoichiometric Anatase 101as described in J. Phys. Chem.
>> C
>> 2007, 111, 16397-16404, I encounter the problem of convergence for SCF
>> cycle. I tried to add 20% more  empty band to the system the problem still
>> laid in. How could I overcome the problem?
>>
>> my input file was attached at the bottom of the mail
>>
>> thank you for reading. Any hints will be appreciated.
>>
>> vega
>>
>>
> ...
>
>
>
>> &SYSTEM
>>                      ibrav = 8,
>>                  celldm(1) =19.3269,
>>                  celldm(2) = 1.1094,
>>                  celldm(3) = 1.7450,
>>                        nat = 71,
>>                       ntyp = 2,
>>                      nosym = .true.,
>>                  ecutwfc   =   30,
>>                  ecutrho   =  300,
>> /
>>
>> &ELECTRONS
>>
>> /
>>
>> &IONS
>>               ion_dynamics = 'bfgs',
>> /
>>
>>
> --
>
> -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
>  Ari P Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/<http://www.iki.fi/%7Eapsi/>
>  IMPMC, CNRS & Université Pierre et Marie Curie
>  Tel: +33-1-4427 7542, Fax: +33-1-4427 3785, GSM: +33-6-6736 3820
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>


-- 
==================================================================================
Vega Lew ( weijia liu)
PH.D Candidate in Chemical Engineering
State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China
******************************************************************************************************************
Email: vegalew at gmail.com
Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, Nanjing,
Jiangsu, China
******************************************************************************************************************
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20090301/30d4dd5c/attachment.html>