[gmx-developers] Implementation of Urey-Bradley

[Mark Abraham]

Hi,

I want to use Urey-Bradley functions in my implementation of CHARMM 
forcefields for gromacs. Reading the source code I see that calc_bonds 
in bondfree.c is where all of the bonded interactions are calculated, 
and that the urey_bradley C function will be called when the topology 
stipulates a U-B function. However that function will issue a fatal 
error because of line 761 of src/gmxlib/bondfree.c:

   gmx_impl("Not implemented yet");

Having read through the remainder of the function, it appears to be 
doing sensible things, but I haven't checked the algebra for the force 
decomposition yet.

Why does someone think this is not implemented yet? What remains to be 
done/tested?

Regards,

Mark Abraham