Chain Bending Potential

Dear Lammps users

I am trying to simulate polymer model where I want to introduce chain bending rigidity through some potential.

So is there any way of introducing it.

Thanks and regards

Yes. Take a look at the angle potentials in lammps.

Dear Mrityunjay,

Hello Mrityunjay. To introduce chain bending rigidity, you can use angle_style cosine and the corresponding coefficients can be specified by using angle_coeff “angle types which angle_style is applied” "Energy parameter for bending rigidity"

Thank you.

Sincerely,

Masato Koizumi

Dear Masato

The angle style cosine works

Thanks and Regards

Hello Mrityunjay,

I just wish to remark that an angle potential is typically only used to introduce stiffness in chains which are very stiff (“wormlike” chains). Typically, in a chemically detailed model for a polymer chain (all atom or united atom, for example), the angle potential will more or less fix bond angles, and chain stiffness comes from the dihedral potential. In a less chemically detailed models (Kremer-Grest, for example) the chain-stiffness is typically coarse-grained out of the model leaving only bead-spring chains with excluded volume.

The angle potential may very well be appropriate for your model, but I thought it was worth clarifying in case your chains are not wormlike.

Best,
-David