[CP2K-user] [CP2K:22089] Re: Energy calculation for charged system LSD/UKS ?

[Andreas Döll]

Hello, 
I just want to update people who may have the same question in the future. 
After further research, my problems could be partially solved with the 
following changes to my input script: 

...
CHARGE +1
    LSD
    MULTIPLICITY 1
...
POISSON_SOLVER
PERIODIC NONE
...
&CENTER_COORDINATES
        &END
...

All of this, and a sufficiently large cutoff (my research shows 5+ A) 
worked for me for case a) where I have a multiplicity of 1. Centering is 
there to prevent problems at the edge of the box with the solver.
Sadly for system b) where the multiplicity is higher, I always get the 
usual wavelet solver issue, even though I 

a) Center my atoms
b) Have a large box (more than 10 A from edges even)
c) have a large cutoff

I keep getting problems with the Wavelet solver at the edge: Usually, the 
error message

 *** WARNING in ps_wavelet_methods.F:238 :: Density non-zero on the edges 
***
 *** of the unit cell: wrong results in WAVELET solver                   
 ***

can be treated with a larger box, it seems to me from looking around the 
Cp2kgroup that higher multiplicity might be difficult, but even when 
increasing the box to have *20+ A vacuum* in each direction I still get a 
problem at the edge. I attach my input script for this issue, maybe 
somebody can spot some obvious mistake quickly! Is this maybe a chemistry 
issue (getting multiplicity wrong? I just cut out a molecule off a larger 
structure, so at each branch of the Triazine, a Hydrogen is missing)

Thank you for your patience
Andreas Döll schrieb am Mittwoch, 4. Februar 2026 um 11:46:43 UTC+1:

> Dear cp2k community,
>
> I have two charged systems I want to perform a single energy calculation.
>
> System a) Neutral molecule with a Lithium at some distance
> System b) Charged molecule (cut out of a larger molecular structure, so 3 
> Hydrogens are missing) 
>
> For both calculations, my energy either diverges or makes jumps. 
> Usually I have performed calculations with neutral molecules, not charged 
> systems, so I am not familiar with the proper procedure. I followed the 
> example give here https://www.cp2k.org/exercises:2014_ethz_mmm:hfx_h2ion 
> I defined my Charge in the DFT section, as well as using LSD option and 
> switched to a Nonperiodic system - as far as I understand this is 
> necessary? Do I need to define the multiplicity of my system as well ?
>
> Cheers, 
> Andreas
>
>
>

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cp2k/fc486a4b-bc1d-46be-a420-43295454d310n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20260205/945375a9/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: spe.inp
Type: chemical/x-gamess-input
Size: 2230 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20260205/945375a9/attachment-0001.inp>