[CP2K-user] how to run brokn spin symmetry calculation with OT

[Tamas K. Stenczel]

Dear cp2k developers and users,

I am working modelling the combustion of small hydrocarbons and have issue 
with spin. I am using CP2K 5.1 right now.

I would like to calculate my system in UKS singlet state, with broken 
symmetry of the alpha-beta channels.  I have understood that this is the 
expected behavior of a large system with many oxygen molecules and the 
result should be better than the singlet with RKS or with spin-symmetric 
UKS (these two give me the same results actually).

Is this possible with the OT methods, how to do it? I have been using 
OT%DIIS for its performance with SCF convergence. Diag and mixing methods 
were not as reliable as this so far, but can perform relaxation of 
multiplicity, which has given me asymetric spins but I cannot use the 
wavefunctions of that to restart OT from, due to the error:

> *******************************************************************************
>  *   ___                                                                       *
>  *  /   \                                                                      *
>  * [ABORT]                                                                     *
>  *  \___/    Number of occupied MOs on restart unit larger than allocated MOs. *
>  *    |                                                                        *
>  *  O/|                                                                        *
>  * /| |                                                                        *
>  * / \                                                          qs_mo_io.F:818 *
>  *******************************************************************************
>
>

some of the input. I have attached an input file of an O2 molecule for 
example.
&DFT
    POTENTIAL_FILE_NAME GTH_POTENTIALS
    UKS TRUE
    MULTIPLICITY 1
    BASIS_SET_FILE_NAME COMBINED_BASIS_TKS32
    &SCF
      MAX_SCF 25
      EPS_SCF 0.0001
      SCF_GUESS RESTART
      &OT
        MINIMIZER DIIS
      &END OT
      &OUTER_SCF
        EPS_SCF 0.0001
        MAX_SCF 4
      &END OUTER_SCF
    &END SCF


Thank you very much,
Tamas K Stenczel
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