[gmx-users] Cutoff length

[David van der Spoel]

Xavier Periole wrote:

> All this is pretty interesting !!
>
>> coulombtype            = Reaction-Field
>> rcoulomb               = 1.8
>
>
> Why so long ?
>
>> epsilon_r              = 100.0
>
>
> Which solvent is this supposed to represent ?
>
>> vdwtype                = Cut-off
>> rvdw                   = 1.0
>
>
> extremely short !
>
>>
>> dispcorr               = no
>
>
> May be you have to check a paper that discribe the force field
> you use and get the same parameters ... You can change the
> properties of you force field by changing the size of a cut-off.
> Longer is not necerally better !!!


Which is described in some detail in our recent paper on water simulations:
http://dx.doi.org/10.1021/ct0502256

We also describe there the effect of using a reaction field dielectric 
constant less than infinite. Our conclusion is that these should be avoided.

>
> XAvier
>


-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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