[CP2K-user] [CP2K:21977] Re: Issues with MO warnings and Cholesky decomposition failure in CP2K with def2-TZVP

[Marcella Iannuzzi]

Hi ..

The warning for the CO calculation is not a real problem. Since the number 
of orbital functions, and consequently the size of  H, is 62, it is not 
possible to generate more than 62 MOs, including occupied and virtual.  The 
advise provided by the warning message is to set ADDED_MOS -1 to request 
the maximum number of available MOs. On the other hand, the code already 
makes this choice and the calculation runs to the end.

The ill conditioned S matrix in the calculation of  the slab is due to the 
choice of the basis set, which is not really suitable for condensed matter 
calculations. To successfully run such systems,  basis sets optimised to 
reduce linear dependencies, as the MOLOPT series (but you can find others 
in the literatures), need to be adopted. 

Regards
Marcella

On Wednesday, November 19, 2025 at 9:38:22 AM UTC+1 scarlet... at gmail.com 
wrote:

> Dear CP2K developers,
>
> I am using CP2K with PBE-D3(BJ) to calculate single-point energies and try 
> to make an output of AO overlap, density matrices, Mulliken and Löwdin 
> populations for CO and CO adsorbed on a Cu slab.
>
> I am facing two problems:
>
>    1. 
>    
>    *MO warning for CO calculations:*
>    When using the def2-TZVP basis set with smearing, CP2K reports:
>    *** WARNING in qs_environment.F:1486 :: More added MOs requested than 
>    *** *** available. The full set of unoccupied MOs will be used. Use *** *** 
>    'ADDED_MOS -1' to always use all available MOs and to get rid of this *** 
>    *** warning. 
>    
>    This occurs even though I explicitly requested 30 MOs in the input.
>    2. 
>    
>    *Cholesky decomposition failure for Cu slab:*
>    When using def2-TZVP for Cu (with or without smearing and CO), the 
>    calculation aborts with:
>    [ABORT] Cholesky decompose failed: matrix is not positive definite or 
>    ill-conditioned fm/cp_cfm_basic_linalg.F:877 
>    
> I would like to ask for guidance on how to avoid these issues. Should I 
> adjust the number of MOs, EPS_DEFAULT, smearing, or other SCF parameters 
> for metal systems with large basis sets? I have no idea about this.
>
> I have attached the input XYZ files and example output files for reference.
>
> Thank you very much for your time and help.
>

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