I think spin unpolarized calculations in that case miss a large exchange
correlation contribution coming from spin alignment.
Isolated Mn2+ should have total magnetization equal to 5 (i think). You
can set this from input. Or you can just let the code find the minimum
by itself.
you can use martina-tuckerman option to decouple periodic images.
It's very important for charged systems.
That should reduce the size of supercell needed to have stable numbers.
stefano
On 10/08/2017 08:50, Iryna Zaporozhets wrote:
I have a single Mn2+ ion in the isolated system with vacuum between
periodic images. Spin-unpolarized calculations run without any errors
so I wonder whether spin-unpolarized calculations produce any useful
results.
Best, Iryna Zaporozhets
2017-08-09 23:39 GMT-07:00 stefano de gironcoli <degir...@sissa.it
<mailto:degir...@sissa.it>>:
depends on your system, is it magnetic ?
metallic aluminum or copper have spin compensated densities and
you can use nspin=1.
nickel or iron are magnetic and nspin=2 is needed.
stefano
On 10/08/2017 08:29, Iryna Zaporozhets wrote:
Dear PW community,
I am working with an open-shell system which requires a lot of
computational efforts. Is it possible to use other options than
spin-polarized calculations (nspin = 2) to reduce computational
cost, for example, restricted open-shell DFT? Is there any
physical meaning to the results obtained with
spin-unpolarized (nspin = 1) calculations in case of the
open-shell system?
Thank you,
Iryna Zaporozhets,
Master student in Chemistry
Kharkiv National University, Ukraine
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