On 30/12/2011 5:30 AM, Olivia Waring wrote:
Hi Mark,

Thanks for your reply! I'm sorry, you're right, as far as I know the manual doesn't actually mention Buckingham pairs generation... but when I set gen-pairs to "yes" and run grompp, I get the following error:

"Generating pair parameters is only supported with LJ non-bonded interactions"

I guess I'm wondering how anyone can use the Buckingham potential at all, since Gromacs does not appear to support pairs generation for the Buckingham or the use of explicitly defined Buckingham pair parameters (when defining [ pairtypes ], you have to give the parameters in LJ form).

Why do you need pairs with your model?

Mark


Thanks so much again,
Olivia


On Wed, Dec 28, 2011 at 8:28 PM, Mark Abraham <mark.abra...@anu.edu.au <mailto:mark.abra...@anu.edu.au>> wrote:

    On 29/12/11, *Olivia Waring *<owar...@princeton.edu
    <mailto:owar...@princeton.edu>> wrote:
    I apologize for the truncated message; I pressed send too soon.

    According to the Gromacs manual, pairs cannot be generated
    automatically for the Buckingham potential,
    Where does it say this?
    but the [ pairtypes ] directive seems to only accept parameters
    in LJ form (i.e. c6 and c12, instead of a, b, and c6). I've been
    looking into ways to interconvert between the two potential
    forms, but haven't found anything... Can anyone who has
    successfully generated a topology using the Buckingham potential
    shed light on this issue?
    You want a 1-4 interaction using Buckingham functional form? If
    so, I don't think GROMACS supports it. If you're trying to combine
    bits of force fields that use L-J with bits of force fields that
    use Buckingham, then that's almost certainly a bad idea.
    Mark

    Thank you so much,
    Olivia

    On Wed, Dec 28, 2011 at 11:05 AM, Olivia Waring
    <owar...@princeton.edu <mailto:owar...@princeton.edu>> wrote:

        Hello Gromacs users,

        I'm using a Buckingham potential for the nonbonded
        interactions in my system, so I have the following lines in
        my forcefield.itp file:

        [ defaults ]
; nbfunc comb-rule gen-pairs fudgeLJ fudgeQQ 2 1 no 1.0 1.0




-- Olivia Waring (???)
        Princeton University '12
        AB Chemistry




-- Olivia Waring (???)
    Princeton University '12
    AB Chemistry


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