Broken Symmetry and Copper

[Henrique Junior]

I'm sorry if I'm bringing up a topic that was already discussed in previous 
threads: Broken Symmetry, but things are still a little confusing to me on 
how too do it in CP2K.

NWChem approaches this problem by generating a state that has “an excess of 
beta electrons”[1] and you move your unpaired electrons to beta (spin 
down). At first I was thinking that CP2K was using a similar approach with 
&ALPHA and &BETA in &BS. Since I'm working with a system with no charge, S 
= 3, and two Cu(II) ( L-CuCl2-L) I have to investigate the magnetic 
coupling between copper centers at various possible distances in my unitary 
cell. Taking a look at the examples I tried this:


&KIND Cu1

ELEMENT Cu

BASIS_SET DZVP-MOLOPT-SR-GTH

POTENTIAL GTH-PBE-q11

&BS

&ALPHA

NEL -1 -1 *(3d9 – One unpaired electron up)*

L 0 2

N 4 3

&END

&BETA

NEL -1 -2 *(3d8 – No unpaired electrons)*

L 0 2

N 4 3

&END

&END

&END KIND

&KIND Cu2

ELEMENT Cu

BASIS_SET DZVP-MOLOPT-SR-GTH

POTENTIAL GTH-PBE-q11

&BS

&ALPHA

NEL -1 -2 *(3d8 – No unpaired electrons)*

L 0 2

N 4 3

&END

&BETA

NEL -1 -1 *(3d9 – One unpaired electron down)*

L 0 2

N 4 3

&END

&END

&END KIND


Does that make any sense?


Thank you so much


[1] -- http://www.nwchem-sw.org/index.php/Special:AWCforum/st/id1680/


---------------

Henrique C. S. Junior - UFRRJ

CP2K - 2.6
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