[MMTK] How to assign different forcefield parameter to the same kind of atoms

[Takefumi SORA]

Hi,

I want to assign different forcefield parameter to
the same kind of atoms.

For example, some "CA"-"CA" bond length is 1.4A, 
other "CA"-"CA" bond length is 1.6A etc.
In the same way, I want to change bond_K parameter,
angle paramter etc.

Does anybody know how to do this ?

Best regards
Takefumi SORA