[Pw_forum] v.6.1 and v.5.40 results differ

[Paolo Giannozzi]

In simple tests I get consistent results across different versions with
spin-polarized vdw-DF2 . Notice that also in your tests the numbers are the
same at the beginning. It seems to me more likely that your system is a
nasty one, with different local minima for spin, so depending on how the
computer wakes up in the morning you end up into a different minimum.

By the way: starting_magnetization should be < 1.

Paolo


On Tue, Aug 29, 2017 at 1:40 PM, Bogdan Yavorskyy <
Bogdan.Yavorskyy at lrz.uni-muenchen.de> wrote:

> Dear developers, dear users,
>
> by applying *v.5.4.0* and *v.6.1* of the parallel PW program to the same
> input file I got different results.
>
> The spin-polarized
>     *nspin=2*,
> antiferromagnetic
>     starting_magnetization(1)=2.0
>     starting_magnetization(2)=-2.0
>     tot_magnetization=0,
> calculations, using exchange-correlation
>     input_dft = '*VDW-DF2'*,
> were done for the system with 42 atoms (1,1'-diiodoferrocene).
>
> The calculation type was "relax" with nstep=1, i.e. self-consistent
> calculations followed by a single step of relaxation.
>
> *VDW-DF2,   NSPIN=2*
>
> *             |  Total energy  | Total force  | Abs.magnetisation*
> *-----------------------------------------------------------------------*
> *ver.5.4  | -1018.91264   |  0.037663   |   7.99*
> *-----------------------------------------------------------------------*
> *ver.6.1  | -1018.88824   |  0.105811   |   5.81*
>
> At the same time, results of the non-magnetic calculations,
>      *nspin=1,*
> with
>      input_dft = '*VDW-DF2*',
> done by the both versions agree well
>
>
> *VDW-DF2,   NSPIN=1*
>
> *             |  Total energy    |  Total force*
> *-------------------------------------------------*
> *ver.5.4  | -1018.876351  | 0.130138    *
> *------------------------------------------------*
> *ver.6.1  | -1018.876354  | 0.130250*
>
> The Input/Output files are in attachment.
>
> Thanks
> Bogdan.
>
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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