[CP2K-user] Spin Contamination "Rule of Thumb?"

[Stephen]

Hi All, 

I'm performing a few calculations of Ni(II) atom supported on a 
metal-organic framework. The Ni(II) atoms can exhibit different spin 
states, which means I must run UKS T while varying MULTI to account for all 
the configurations. 

Is there a specific rule for spin contamination when looking at the S**2? 
For example, 

  Ideal and single determinant S**2 :                   12.000000      
12.019722

I've assumed that this particular structure has no spin contamination, I 
have some other calculations where the difference between the ideal and 
single determinant spin states is much larger (Delta_S**2 = ~2.00). 

Does anyone have an appropriate cutoff for spin contamination? 

With much appreciation, 

Stephen 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210122/29f314ac/attachment.htm>