MULLIKEN CHARGE

[Matt W]

Hi Josip,

Mulliken charges are not real observables - they are strongly dependent on 
the basis set, and they do not converge as you make the basis set complete. 
Check a quantum chemistry textbook for a good discussion ('Computational 
Chemistry', Errol Lewars for instance).

Something more quantitative can come from something like Bader charge 
analysis (which needs external processing of a total_charge_density cube 
file).

Matt

On Monday, December 19, 2016 at 3:56:55 PM UTC, Josip Lovrić wrote:
>
> Dear CP2K community,
>
> Recently I was working on NO2-dimer and now I need help from you. Thing is 
> that I am running gas phase calculation of NO2 cis-dimer. After program 
> successfully  finish GEOMETRIC OPTIMIZATION output configuration is 
> consistent with already published papers. Problem is in the MULLIKEN 
> charges. Charges are too small and not consistent with published values(I 
> am using same basis set).
>
> !-----------------------------------------------------------------------------!
>                      Mulliken Population Analysis
>
>  #  Atom  Element  Kind  Atomic population                           Net 
> charge
>        1     N        1          4.968657                             
>  0.031343
>        2     O        2          5.852787                             
>  0.147213
>        3     O        2          6.191534                             
> -0.191534
>        4     N        1          4.928901                             
>  0.071099
>        5     O        2          6.056358                             
> -0.056358
>        6     O        2          6.001764                             
> -0.001764
>  # Total charge                             34.000000                 
>  0.000000
>
>
>  !-----------------------------------------------------------------------------!
> I am using BLYP functional with dispersion corrections and TZV2P basis set 
> with pseudo-potentials. Charges are becoming more physical when performing 
> all electron calculation, they increase for factor ~10. 
> For DZVP basis set charges increase little, but still to low:
>
>  !-----------------------------------------------------------------------------!
>                      Mulliken Population Analysis
>
>  #  Atom  Element  Kind  Atomic population                           Net 
> charge
>        1     N        1          4.951639                             
>  0.048361
>        2     O        2          5.822911                             
>  0.177089
>        3     O        2          6.202144                             
> -0.202144
>        4     N        1          4.858609                             
>  0.141391
>        5     O        2          6.103330                             
> -0.103330
>        6     O        2          6.061367                             
> -0.061367
>  # Total charge                             34.000000                 
> -0.000000
>
>
>  !-----------------------------------------------------------------------------!
>   Am I doing something wrong? Do you have any explanation for this results?
> I would really appreciate. 
>
> I am putting in attachment my input and output files. 
>
> Best wishes
> Josip
>
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