[Pw_forum] something about Pt.pw91-n-van.UPF

[Gabriele Sclauzero]

Dear Vega,

    as pointed out by Prof. Eyvaz, your system is to be considered "metallic", in the 
sense that Pt is an open shell atom and there is a set of nearly degenerate levels (nearly 
because the crystall symmetry breaks the spherical symmerty of the atom) which is not 
full. The changes in charge density during self-consistency move these levels up and down 
a bit every cycle, so that their occupancy also changes and therefore the charge density 
changes somehow "discontinuously" from step to step, preventing the calculation from 
reaching self-consistency.

In order to get a better estimate of the isolated atom energy, I suggest to do a spin 
polarized calculation (i.e. nspin=2) either using a very small smearing (and check 
converge with respect to degauss), or fixing occupations (specify occupations='from_input' 
in the electrons namelist and add the input card OCCUPATIONS after the namelists).
You can also fix the total magnetization (=2.0) or, equivalently, the spin multiplicity 
(=3)instead of occupations.

Other suggestions:

vega lew wrote:
>  &CONTROL                                                                                 
> ,                                                  
>                        nstep = 1000 

you don't need to specify this in scf calculations. If you want to increase the maximum 
number of iterations in the scf cycle the corresponding key is electron_maxstep in electrons.

> ,                                                    
>                        nosym = .ture. 
.TRUE.

Regards,

GS

> 
> vega
> 
> -- 
> ==================================================================================
> 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
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> Email: vegalew at gmail.com <mailto:vegalew at gmail.com>
> Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, 
> Nanjing, Jiangsu, China  
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