[Pw_forum] Problem with PAW vs. USP

[Giovanni Cantele]

Indeed, just to give an example of the case under study (isolated Zr atom):
hexagonal supercell
ibrav=4,
a=12, c=15
ATOMIC_POSITIONS {crystal}
Zr    0.0  0.0  0.0
produces 24 Sym. Ops., total energy -306.74916039 Ry and total magnetisation=2

cubic supercell
ibrav=1,
a=12
ATOMIC_POSITIONS {crystal}
Zr    0.0  0.0  0.0
produces 48 Sym. Ops., total energy -306.75705192 Ry and total magnetization=4!!!!!

orthorhombic supercell
ibrav=8,
a=12
b=13
c=14
ATOMIC_POSITIONS {crystal}
Zr    0.1  0.2  0.3
produces 4 Sym. Ops., total energy -306.75699428 Ry and total magnetization=4, so very similar to the cubic supercell


> On 14 Oct 2015, at 13:42, Lorenzo Paulatto <lorenzo.paulatto at impmc.upmc.fr> wrote:
> 
> It is really quite tricky to get the isolated atom energy right.
> 
> You may have to use nosym=.true., to specify a small smearing, to force 
> different magnetizations and even to specify manually the occupations.
> Even the same input can produce different result on different machine because 
> of different FFTW implementations.
> 
> kind regards
> -- 
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> +33 (0)1 44 275 084 / skype: paulatz
> http://www.impmc.upmc.fr/~paulatto/
> 23-24/4é16 Boîte courrier 115, 
> 4 place Jussieu 75252 Paris Cédex 05
> 
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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele