[Pw_forum] convergence is hard to achieve using PAW

[Filipe Camargo Dalmatti Alves Lima]

Dear Ganjar,


Question zero: did you achiev a convergence using ultrasoft
pseudopotentials using this input?  If your answer is yes, the rest of the
email might not help you...

I think you misunderstood the option ibrav=0.
As you may see in the input data description, when you select ibrav=0, it
is written you should set only A or celldm(1).

If it is the case you have A, B and C and right angles, it means you cell
is orthorombic (ibrav=8). Of course you may use ibrav=0, however, I am not
sure if the code understand A, B and C. Maybe, you should write B and C in
terms of A value into the cell_parameter card. I am not an expert using
ibrav=0 (I have never used, to be honest), sorry if I told you something
you already had checked.

 If your input is ok, you should be able to measure the atom-atom distances
and be sure they are the expected ones. My guess is that you will figure
out that the cell is smaller than you want: the program is just ignoring
the B and C parameters.

I have already had problems setting wrong cell parameters, resulting in no
convergence.

I hope it helped,

Best regards,

Filipe Dalmatti Lima
PhD Candidate
University of São Paulo, Physics Institute, Materials Physics Department,
Brazil.

On Monday, March 3, 2014, Ganjar Kurniawan <zargan88 at gmail.com> wrote:

> Dear QE users
>
> This is the first time I use the PAW pseudopotential. I have calculated
> the system using the PAW pseudopotential, but the convergence is very hard
> to achieve. I treat the system as insulator (according to the experiment)
> and I have tried to vary the mixing beta value from 0.7 until 0.2 (the
> latest which I give with the difference is 0.1 gradually) but the latest
> result become worst than the before.
>
> The question is whats wrong with my input??
> how about the value of ecutrho I have given??
>
> What I must to do??
>
> input and output file are attached
>
> I hope your advice please..
>
> Thank you
>
> Best Regard....
>
> Ganjar Kurniawan
> Bandung Institute of Technology
>
>

-- 
_________________________________________
Filipe Camargo Dalmatti Alves Lima
PhD Student
University of São Paulo, Physics Institute, Materials Physics Department,
Nanomol Group, Brazil.
Phones:    (11) 3091-6881  (USP)
                (11) 97408-2755 (Vivo)
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