[gmx-developers] Accessing forcefield data

[David]

On Tue, 2004-07-06 at 23:17, Martin Ulmschneider wrote:
> Hi,
> 
> I am adding an extra force in gromacs. This force depends on the 
> forcefield values of r0 and angle0 (i.e. the forcefield bondlength and 
> angle). Hence i would prefer to access r0 and angle0 in the CODE rather 
> than writing a new forcefield file loader. Is this very difficult to access?
Not very...
There is a Urey-Bradley term in the bonded forces which should have all
the information you need. (src/gmxlib/bondfree.c)

> Best wishes,
> Martin
> 
> David wrote:
> > On Tue, 2004-07-06 at 21:41, Martin Ulmschneider wrote:
> > 
> >>Hi,
> >>
> >>I would like to check the forcefield data (i'm interested in the 
> >>forcefield bond lengths r0 and angles alpha0) in gromacs. Could you 
> >>please tell me which structure they are in and how i can access them? 
> >>E.g. the mass of atom j can be accessed by  mass = top->atoms.atom[j].m. 
> >>Is there a simlar way to access b0 and alpha0?
> >>
> > 
> > wouldn't you rather browse through the text files in share/top ?
> > otherwise you'll have to decipher the idef structure of the topology.
> > 
> >>Many thanks!!!
> >>Martin
> >>
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-- 
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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