AMBER Archive (2009)
Subject: Re: [AMBER] help with parameters for ions
From: InSuk Joung (i.joung_at_gmail.com)
Date: Tue Jun 02 2009 - 10:28:55 CDT
You need to show the complete script of leap. I suspect that your atom
types are different from the names in the new frcmod file.
If your concern is the crystallization of KCl, you'd better use TIP4PEW or
SPC/E water and their ions. The solubilities of TIP3P-compatible ions are
also low. We are going to publish the data soon.
On Tue, Jun 2, 2009 at 11:10 AM, rebeca <rebeca_at_mmb.pcb.ub.es> wrote:
> Thank you very much for your answer, I was using Amber9, but now I have
> seen those files in Amber10, which is great.
> I have another question. To load these new parameters, I use:
> loadamberparams frcmod.ionsjc_tip3p
> and then I do:
> addions mol Na+ 30 Cl- 30
> However, I have checked the amber topologies generated with both parameters
> sets (via vimdiff) and they are exactly the same. So, these new parameters
> are not being considered.
> Is there anything more I should do for including them in the right way?
> Thank you very much for your help,
> On Tue, 2 Jun 2009 09:46:40 -0400, "David A. Case"
> <case_at_biomaps.rutgers.edu> wrote:
> > On Tue, Jun 02, 2009, rebeca wrote:
> >> I am doing simulations using a KCl concentration 1M and I have problems
> >> of
> >> crystallization of ions in the simulations. I have seen in the
> >> that this is normal with Amber parameters for ions.
> >> I have found a paper
> >> "Determination of Alkali and Monovalent Ion Parameters for Use in
> >> Explicitly Solvated Biomolecular Simulations"
> >> S Joung, Thomas E Cheatham, J. Phys. Chem. B, Vol. 112, No. 30. (1 July
> >> 2008), pp. 9020-9041.
> >> http://www.citeulike.org/user/softsimu/article/3863549
> > Frcmod files for these parameters are in the frcmod_ionsjc_* files in
> > $AMBERHOME/dat/leap/parm. You can use those directly, and also see how
> > frcmod files were created, in case you want to use your own or other
> > parameters.
> > ...hope this helps...dac
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> Rebeca García Fandiño
> Molecular Modelling and Bioinformatics Group
> Institut de Reçerca Biomèdica
> Parc Cientific de Barcelona
> 08028 Barcelona
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