[gmx-users] VDW Cut-off vs Switch with CHARMM force field

[James Krieger]

CHARMM is generally used with vdw switching between 1.0 and 1.2 nm - I presume it must be more accurate that way. There are a number of discussions on this already. Justin recommended using rlistlong 1.4 as well I think. You might want to use a short range cutoff (rcoulomb) of 1.2 for PME as well. That is what was done in the Bjelkmar et al paper where CHARMM27 was implemented in GROMACS (http://pubs.acs.org/doi/full/10.1021/ct900549r).

Best wishes
James

On 24 Aug 2013, at 23:08, Gianluca Interlandi <gianluca at u.washington.edu> wrote:

> Hi!
> 
> I am running explicit solvent simulations with the CHARMM force field implemented in gromacs 4.6.3. For VDW I have been using:
> 
> rlist    = 1.0
> vdw-type = Cut-off
> rvdw     = 1.0
> 
> in conjunction with PME and rcoulomb=1 for electrostatics.
> 
> I wonder whether it would be more accurate to use instead a switching function for VDW between 0.8 and 1.0 and a larger rlist:
> 
> rlist       = 1.2
> vdw-type    = Switch
> rvdw_switch = 0.8
> rvdw        = 1.0
> 
> My question is: does switching between 0.8 and 1.0 generate less artifacts than abrupt truncation at 1.0 nm for VDW?
> 
> Thanks!
> 
>     Gianluca
> 
> -----------------------------------------------------
> Gianluca Interlandi, PhD gianluca at u.washington.edu
>                    http://artemide.bioeng.washington.edu/
> 
> Research Scientist at the Department of Bioengineering
> at the University of Washington, Seattle WA U.S.A.
> -----------------------------------------------------
> -- 
> gmx-users mailing list    gmx-users at gromacs.org
> http://lists.gromacs.org/mailman/listinfo/gmx-users
> * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
> * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-request at gromacs.org.
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists