Using FENE and quartic bonds together

Hello,

I would like to ask about using FENE and quartic bonds together.

I want to use both bond types together using,

bond_style        hybrid fene quartic
bond_coeff        1 fene 30.0 1.5 1.0 1.0
bond_coeff        2 quartic 1200.0 -0.55 0.95 1.3 34.6878

but it seems like it is not allowed to use FENE and quartic together; it cannot hybridize bond styles with different topology settings.

I remember I was able to use these two bonds together using hybrid bond style before, so I just wanted to ask if there was an update regarding this.

I guess possible solution to this is to approximate FENE with quartic bond according to the parameters written in the manual,

bond_style        quartic
bond_coeff        1 1200.0 -0.55 0.25 1.3 34.6878
bond_coeff        2 1200.0 -0.55 0.95 1.3 34.6878

by using B2 as 0.25 instead of 0.95 (bond id 1 is replacing FENE here).

Please let me know if this would be fine to approach this problem.

Thank you!

You cannot mix bond styles that are “breakable” (like quartic) with bond styles that are not.

or use the bond_write command to create a table for the quartic bond style and use
bond style table instead.

Whatever choice you make, you need to construct some tests to validate it.

You may also be able to use bond_style lepton to specify an analytical expression for the bond potential, if the speed penalty is acceptable for your use case.

Thank you very much for the suggestions!

I will try to incorporate bond_write or bond_style lepton.

I will also try to update if I find a suitable solution to my test case.