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    Hello <span style="font-family: arial; white-space: pre-wrap; line-height: 23.32400131225586px;">Xiaobao,

do you mean the output (self-consistent) charge is not 2.0? There is nothing in the standard SCC-DFTB model to require the output charge to match the starting initial charges. If you want to force the C2 molecule to be +2, the two possibilities that have been explored (and are not in the standard DFTB+ code) are to either use a constrained DFTB method or to apply time propagation from an initial state which introduces a +2 molecule into the system.

Regards

Ben
</span><br>
    <div class="moz-cite-prefix">On 26/03/16 14:14, jsxz wrote:<br>
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      cite="mid:2c4560c8.488a.153b3471392.Coremail.jsxzzhangchao@126.com"
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        <div>Dear <span style="font-family: arial; white-space: pre-wrap; line-height: 23.32400131225586px;">Bálint, </span></div>
        <div><span style="font-family: arial; white-space: pre-wrap; line-height: 23.32400131225586px;">     I calculate the incident carbon ion (C2+) impinging the carbon nanotube. When I set the charge of the incident carbon ion, but find the charge does not work.</span></div>
        <div><font face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;">Hamiltonian = DFTB {
  SCC = Yes
  SCCTolerance = 1.0e-5
  MaxSCCIterations = 100
  Mixer = Broyden {}
  MaxAngularMomentum = {
    C = "p"
  }
  Charge= 2
   InitialCharges={
     AtomCharge={
    Atoms=1  #  incident carbon ion
    ChargePerAtom= 2  </span></font><span style="font-family: arial; line-height: 23.32400131225586px; white-space: pre-wrap;">#  the charge of incident carbon ion, C2+</span><font
            face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;">
    }
   }</span></font></div>
        <font face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;"> Filling = Fermi {
    Temperature [Kelvin] = 1000.0
  }
  SlaterKosterFiles = {
    C-C = "C-C.skf"
  }
  KPointsAndWeights = SupercellFolding{
  1   0   0
  0   1   0
  0   0   9
  0.0 0.0 0.0
  }                                      
  ReadInitialCharges = No                       
}</span></font>
        <div><font face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;">
</span></font></div>
        <div><font face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;">The running result shows the initial charge of the incident carbon ion is about 4.0 in the geom.out.xyz, I do not know why it is not 2.0 (C2+).</span></font></div>
        <div><font face="arial"><span style="line-height: 23.32400131225586px; white-space: pre-wrap;">
</span></font></div>
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          <p style="margin: 0px; padding: 0px; border: 0px; outline:
            0px; font-stretch: inherit; font-size: 15px; line-height:
            18px; vertical-align: baseline; font-family: 돋움;">Thanks a
            lot!</p>
          <p style="margin: 0px; padding: 0px; border: 0px; outline:
            0px; font-stretch: inherit; font-size: 15px; line-height:
            18px; vertical-align: baseline; font-family: 돋움;"> </p>
          <p style="margin: 0px; padding: 0px; border: 0px; outline:
            0px; font-stretch: inherit; font-size: 15px; line-height:
            18px; vertical-align: baseline; font-family: 돋움;"> </p>
          <p style="margin: 0px; padding: 0px; border: 0px; outline:
            0px; font-stretch: inherit; font-size: 15px; line-height:
            18px; vertical-align: baseline; font-family: 돋움;">Sincerely,</p>
          <p style="margin: 0px; padding: 0px; border: 0px; outline:
            0px; font-stretch: inherit; font-size: 15px; line-height:
            18px; vertical-align: baseline; font-family: 돋움;"><br>
          </p>
          <div><span style="font-family: arial; white-space: pre-wrap; line-height: 23.32400131225586px;"> Xiaobao</span></div>
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    <br>
    <pre class="moz-signature" cols="72">-- 
      Dr. B. Hourahine, SUPA, Department of Physics,
    University of Strathclyde, John Anderson Building,
            107 Rottenrow, Glasgow G4 0NG, UK.
    +44 141 548 2325, <a class="moz-txt-link-abbreviated" href="mailto:benjamin.hourahine@strath.ac.uk">benjamin.hourahine@strath.ac.uk</a>

2013/4 THE Awards Entrepreneurial University of the Year
      2012/13 THE Awards UK University of the Year

   The University of Strathclyde is a charitable body,
        registered in Scotland, number SC015263</pre>
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