On Fri, Sep 13, 2013 at 9:44 AM, Tanmoy Paul <tanmoy635.gmail.com> wrote:
> Hi,
> I am doing ONIOM calculations for RESP charge setup using gaussian
> 09. Now during optimization the VDW parameters for HW and HO are asked
> to be set as they are being set to zero in 'amber.prm' incorporated
> to gaussian 09.
That is because they _are_ set to 0 in most versions of the Amber force
field.
The idea is that the hydrogen is completely enclosed in the vdW radius of
the oxygen atom it is bonded to.
I have searched for the missing parameters in AMBER12
> parm . I have found two different VDW radius for HO ( one in
> 'parm99EP.dat' and another in 'parmpol12.dat') and no parameter
> corresponding to HW. I am confused regarding which one to pick for HO
> and where to find the parameters for HW.
>
Look in parm99.dat or parm10.dat or something like that. You are looking
at the polarizable force field parameter files (parmpol12.dat) and the
extra points (lone pairs)-based force field (parm99EP.dat). I believe that
ONIOM uses the standard, 'fixed-charge' force field.
HTH,
Jason
--
Jason M. Swails
BioMaPS,
Rutgers University
Postdoctoral Researcher
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Received on Fri Sep 13 2013 - 07:30:02 PDT
