[CP2K:4909] Charge calculation -- Charged system

[hut... at chem.uzh.ch]

Hi

with any standard GGA you will get "charge transfer" at any
distance of the proton. The result will be un-physical.

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
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-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: Sandeep Kumar Reddy 
Sent by: cp... at googlegroups.com
Date: 01/21/2014 09:45AM
Subject: Re: [CP2K:4909] Charge calculation -- Charged system

Dear Apsi and Hutter,
                                         Thank you for the reply. Yes, your guess is correct. I used HF method in Gaussian09 software. I repeated the charge calculation with DFT method, and as you said, i got the similar charges as that i found using cp2k software.  

My purpose of these test runs is study "the proton irradiation of a surface". If the charge on the proton is not +1, then is it correct to assume it as a proton as when it approaches the surface, there will be a transfer of charge between proton and the surface. Kindly let me know if this is wrong. 

Thanks.

 
Regards,
Sandeep 

 



 


On Tue, Jan 21, 2014 at 1:49 PM,  <hut... at chem.uzh.ch> wrote:
 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
 your Gaussian calculation.
 
 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
 ---------------------------------------------------------------
 
 -----cp... at googlegroups.com wrote: -----
 To: cp... at googlegroups.com
 From: Sandeep Kumar Reddy
 Sent by: cp... at googlegroups.com
 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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 [attachment "cp2k.inp" removed by Jürg Hutter/at/UZH]
 

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