[Pw_forum] fluctuation in SCF energies of CO adsorbed on Pd110

[Paolo Giannozzi]

I would increase degauss by at least a factor 10.
The kind of behavior you have is typical of metals
that are not treated as such. degauss=0.001 is
very small and it may not have enough effect.

For a Gamma-only calculation, K_POINTS gamma is 
faster (allows the usage of memory- and cpu-saving 
tricks). 1000 bands (instead of 1300) should be 
sufficient. For a first test you should use smaller
cutoffs.

Paolo

On Sun, 2014-04-20 at 09:20 -0700, David Foster wrote:
> Dear users
> 
> I have prepared an input for interaction between CO and Pd(110). I optimized 3*3*3 supercell of Pd bulk, and then cleaved a 110 surface and constructed a slab. I inserted CO molecule which has been optimized with QE5.0.2 in it. Now, I try to optimize this mixed system (CO+Pd(110)).
> 
> My main problem is that in scf I see the fluctuation in energies. My input and output has been attached. In all calculations I used QE5.0.2 and the same USPP. I used PBE DFT in the PP. I used nspin=2 due to the presence of oxygen atom. I introduced start_magnetization for all species. I fixed three bottom layers in the cell. I used ibrav=14 to optimize bulk phase of Pd, and didn't change it in all computation.
> I used degauss=0.001RY. In addition I used smearing technique for both bulk and slab.
> 
> The run is continuing, but I think finally, I will encounter with problem.
> 
> Any idea for rapid convergence and solve the issue in fluctuation energy is appreciated.
> 
> 
> 
> 
> Regards
> 
> David Foster
> 
> Ph.D. Student of Chemistry
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222