# [CP2K:4905] Charge calculation -- Charged system

hut... at chem.uzh.ch hut... at chem.uzh.ch
Tue Jan 21 08:19:47 UTC 2014

```Hi

you are calculating a water molecule with a distant proton.
GGA functionals are known to get this wrong. They fail to
localize the charge and give a 'smeared' charge distribution.
See the 0.5 charge on the lone H.
HF on the other hand localizes the charge, as you can see in

regards

Juerg Hutter

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie                  FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

From: Sandeep Kumar Reddy
Date: 01/21/2014 06:55AM
Subject: [CP2K:4905] Charge calculation -- Charged system

Dear All,
I am trying to calculate atomic charges of a system whose total charge is +1. I am not able to get charges correctly as expected.

For the sake of better understanding, i have taken an easy system which consists of 1 water molecule and 1 H atom (Total 4 atoms).

First, I used Gaussian software to calculate the atomic charges on this system.

Mulliken atomic charges: (Method:  hf 6-31g(d))
1
1  O   -0.857873
2  H    0.424054
3  H    0.433819
4  H    1.000000

Sum of Mulliken atomic charges =   1.00000

Using CP2K, i have got the following charges.

MULLIKEN POPULATION ANALYSIS

#  Atom  Element  Kind  Atomic population                Net charge
1     O        1          5.956324                  0.043676
2     H        2          0.814162                  0.185838
3     H        2          0.809985                  0.190015
4     H        2          0.419529                  0.580471
# Total charge                  8.000000                  1.000000

In case of atom centered basis set, i can clearly see +1 charge is localized on 1 H atom where as it is not the case using mixed basis set. Could anybody help me in this regard? The cp2k input file is enclosed.

Thanks.

Regards,
Sandeep

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