How to get the parameters of Lennard-Jones potential?

[pincher-chen]

Hi,

I am new to QuickFF and try to fit a suite parameters for my system. Following by the examples in QuickFF/share/systems, I can get parameters of covalent interactions and electrostatic contribution easily. However, as for Van der Waals part (no matter LJ or MM3), there are little descriptions. As help informations say:

$ python ../../../scripts/qff.py  --help
....
 --vdw VDW             A Yaff parameters file defining the van der Waals
                        contribution of the force field.
  --vdw-rcut VDW_RCUT   The real space cut off for the van der Waals
                        interactions.

Another Yaff parameters file is needed, then I read the documents of Yaff and check the examples in Yaff. I am still confused how to get the parameters of Van der Waals interactions. Can you show me some tips or give me a example.

Thank you.

[lvduyfhu]

Hi,
QuickFF only deals with the determination of the covalent parameters. For the estimation of electrostatic parameters we refer to other programs (eg. Horton, http://theochem.github.io/horton/) and for the determination of van der Waals parameters, we refer to other force fields (UFF, MM3, GAFF, ...).
kind regards,
Louis