Hello, the method I know to obtain just a repulsive LJ potential is to calculate the minimum of the potential, then set the cut-off to the minimum and shift the whole potential by the amount of the minimum. Then you just have a repulsive LJ interaction. However as soon as more than one particle type is involved you will run into problems with this method, because different cutoffs will arise. So it will be necessary to form tables and use them.
/Flo On 28.07.10 14:31, Amir Marcovitz wrote: > Hi Ehud, > > Did you mean that i can simply specify Sigma and Epsilon? > The thing is that i didn't want to obtain a zero potential , but > rather maintain the repulsive term of the LJ interaction. > What would you specify then, for the C6 and C12 parameters? > > Amir > > On Wed, Jul 28, 2010 at 3:00 PM, Ehud Schreiber > <[email protected] <mailto:[email protected]>> wrote: > > Hi Amir, > > > > Are you sure you’re giving the parameters indeed as C_6 and C_{12}? > > According to the combination rule in the [ defaults ] section, you > may be giving the two parameters directly as sigma and epsilon; > sigma=0 (as well as epsilon=0) would give an identically zero > potential . See sections 5.3.3 and 5.7.1 in the manual (version 4.0). > > > > > -- > gmx-users mailing list [email protected] > <mailto:[email protected]> > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at http://www.gromacs.org/search before > posting! > Please don't post (un)subscribe requests to the list. Use the > www interface or send it to [email protected] > <mailto:[email protected]>. > Can't post? Read http://www.gromacs.org/mailing_lists/users.php > > -- Florian Dommert Dipl. Phys. Institute for Computational Physics University Stuttgart Pfaffenwaldring 27 70565 Stuttgart Germany Tel: +49 - 711 / 6856-3613 Fax: +49 - 711 / 6856-3658 EMail: [email protected] Home: http://www.icp.uni-stuttgart.de/~icp/Florian_Dommert !! PGP-ENCODED emails preferred !!
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