[gmx-users] K+ atom type is not found in GROMOS96

Xavier Periole x.periole at rug.nl
Thu Jan 27 11:06:32 CET 2005

Binbin Liu wrote:

>Dear all,
>I used genion to add K+ ions to the system. Then I started to generate .tpr 
>for the simulation. However grompp always gives the warning that "atomtype 
>'K' is not found". I checked .atp file under /top and find that there is no 
>'k' atom type in ff43a1.atp file. I used GROMOS96 FF to generate .gro and 
>topology files. So what shall I do to let the program knows 'k' ?

Potassium is not defined in GROMOS !! You might want to switch to Na if 
you are neutralizing your system. Na+ and Cl- are generaly used for this 



   Xavier Periole - Ph.D.

   Dept. of Biophysical Chemistry / MD Group
   Univ. of Groningen
   Nijenborgh 4
   9747 AG Groningen
   The Netherlands

   Tel: +31-503634329
   Fax: +31-503634800
   email: x.periole at rug.nl
   web-page: http://md.chem.rug.nl/~periole


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