[Pw_forum] Problem With Spin-Unrestricted Calculation for Adsorbed Singlet O2

Paolo Giannozzi paolo.giannozzi at uniud.it
Sun Sep 29 23:09:48 CEST 2013

On Sat, 2013-09-28 at 18:38 -0400, Vic Bermudez wrote:

> My intuition is that I should just ignore this since what is
> probably happening is that the program is trying to reach the
> lower-energy, spin-contaminated state but can't because the 
> system is locked at S = 0. Is this correct, or is there a 
> real problem here ?

there is a real problem but not a problem for you: if the 
magnetization is constrained, there is no reason to make 
an additional step without electronic history (since it is
done to prevent the unlikely but not impossible case of a 
system being trapped into a zero magnetization state during

There might be also another real but minor problem: the case 
"spin-polarized optimization + final step without electronic 
history + electric field" (a rather unusual combination) might 
not be properly implemented.

Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222 

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