[Pw_forum] Re [7] : US-PP of Au

[Gabriele Sclauzero]

Dear Reza,

Le 13-set-2010 à 20:49, reza shidpoor <rezashidpoor at gmail.com> a écrit :

> 
> Dear Gabriele
> 
> Thank you for your comments in pwscf forum.
> 
> I performed your suggestion that ecut is set to 32 Ry. The structure was relaxed

So you can confirm that with this cutoff it works, do you?


> and  I repeated with ecut=20 , 22 Ry.

Why do you want to do so?

If the cutoff id too low the forces are not described correctly and the ralaxation algorithm might fail to converge.

> It seems that the structure did not relaxed with this point "
> 
>     .............
>      ...........
>      the Fermi energy is    -5.0636 ev
> 
> !    total energy              =    -262.94392529 Ry
>      Harris-Foulkes estimate   =    -262.94392533 Ry
>      estimated scf accuracy    <       0.00000006 Ry
> 
>      The total energy is the sum of the following terms:
> 
>      one-electron contribution =    -323.90644330 Ry
>      hartree contribution      =     178.85727642 Ry
>      xc contribution           =    -104.02662243 Ry
>      ewald contribution        =     -13.85257067 Ry
>      smearing contrib. (-TS)   =      -0.01556530 Ry
> 
>      convergence has been achieved in   2 iterations
> 
>      Forces acting on atoms (Ry/au):
> 
> 
>      negative rho (up, down):  0.998E-04 0.000E+00
>      atom   1 type  1   force =     0.00000000    0.00223711    0.00000000
>      atom   2 type  1   force =    -0.00165978   -0.00111856    0.00000000
>      atom   3 type  1   force =     0.00165978   -0.00111856    0.00000000
> 
>      Total force =     0.003608     Total SCF correction =     0.000988
>      SCF correction compared to forces is too large, reduce conv_thr

Besides increasing the cutoff, you might need to decrease this threshold on order for the forces to be perfectly consistent with the total energy.


> 
>      The maximum number of steps has been reached.
> 
>      End of BFGS Geometry Optimization
> Begin final coordinates
> 
> ATOMIC_POSITIONS (angstrom)
> Au       0.000000000   0.248435531   0.000000000
> Au      -2.339313337   1.325352234   0.000000000
> Au       2.339313337   1.325352234   0.000000000
> End final coordinates
> 
> ........................
> ........................
> 
> Questions :
> 
> 1) The electron_maxstep is equaled 100. What is purpose of "number of states" ?

???
You are confusing number of states with number of electrpnic steps and perhaps also with ionic steps. Please spend some time reading the manual and some examples or tutorials.

> 
> 2) Should I consider system to be semiconducting  If I want to simulate 4-atoms cluster?

If you are not sure, you can treat your system as metallic with a small smearing and then, if it turns out to have a gap, reduce/remove the smearing.

 GS
> 
> 
> Best Regards,
> Reza.Shidpour
> SUT
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