[CP2K-user] Error with specifying a negative multiplicity

[Jae Eun Lee]

Dear cp2k users

Hi, I am wondering whether I can specify negative multiplicity for a 
particular system. I have put multiplicity as -2 for an anion molecule for 
a DFT calculation and I got the following error : 

 **** WARNING in qs_environment.F:1295 :: More beta than alpha MOs          
****
* *** requested. The number of beta MOs will be reduced to the number alpha 
****
* *** MOs.                                                                  
****


* ********************************************************************************
* *   ___                                                                  
     **
* *  /   \                                                                  
    **
* * [ABORT]                                                                
     **
* *  \___/                             CPASSERT failed                      
    **
* *    |                                                                    
    **
* *  O/|                                                                    
    **
* * /| |                                                                    
    **
* * / \                                                  
 qs_environment.F:1300 **
* ********************************************************************************


* ===== Routine Calling Stack =====*

*            2 qs_init_subsys*
*            1 CP2K*

Based on the last discussion by Pavan in April last year, it seems like 
cp2k does not support a way to generate configuration where the unpaired 
electron is in the spin down state (beta). But I would like to ask once 
again if someone has come up with a way to specify beta spin state for the 
unpaired electron. I understand that alpha and beta states should be 
degenerate in the absence of magnetic field but my system needs to treat 
alpha and beta spin states separately.

*Background of my system (just in case)*

I am studying a system where an electron is transferred from an organic 
molecule to a oxygen molecule. Let A be the organic molecule (IDFBR) and B 
be the oxygen molecule and the electron transfer can be described by the 
following equation:

[A]- + [B]  --> [A] + [B]-

Since the ground state of oxygen molecule is triplet and anion organic 
molecule is doublet, I believe that the electron can only transferred from 
the anion organic molecule if the spin states of the electrons in A- and B 
are correctly aligned. (alpha electron at the SOMO of [A]- if electrons at 
the SOMOs of B are beta or  beta electrons at the SOMO of [A]- if electrons 
at the SOMOs of B are alpha).


[image: electron transfer.png]                                              
                  [image: electron transfer2.png]
Electron transfer not possible                                              
 Electron transfer possible


Therefore, I need to study the particular system where unpaired electron of 
A has opposite spin state as B.

Thank you so much for your time and I would really appreciate any comments 
/ help on this.

kind regards

jae
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210420/d5fab0f9/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: electron transfer.png
Type: image/png
Size: 23261 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210420/d5fab0f9/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: electron transfer2.png
Type: image/png
Size: 12004 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210420/d5fab0f9/attachment-0001.png>