Multi/harmonic options for bond_style and angle_style

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#1

Dear Dr. Axel Kohlmeyer and LAMMPS Users,

Hello Dr. Kohlmeyer. I see that dihedral_style multi/harmonic command allows the summation of harmonic terms. I was curious if there is the same options for bond_style and angle_style where I can obtain a bond and angle potential consisting of a sum of multiple harmonic terms.

The manual does not specify multi/harmonic options for bond_style and angle_style. I used the hybrid command but, unfortunately, it seems that I cannot use the same bond style twice. I would greatly appreciate if I could request for any advice or suggestions.

Thank you.

Sincerely,

Masato Koizumi

#2

See the bond class2 formula. Also you could tabulate any bond
potential you like and use bond table.

Steve

#3

See the bond class2 formula. Also you could tabulate any bond
potential you like and use bond table.
Steve

some links which might be relevant:
https://lammps.sandia.gov/doc/bond_table.html
https://lammps.sandia.gov/doc/bond_class2.html
https://lammps.sandia.gov/doc/angle_table.html
https://lammps.sandia.gov/doc/angle_class2.html
https://lammps.sandia.gov/doc/dihedral_table.html
https://lammps.sandia.gov/doc/dihedral_class2.html
https://lammps.sandia.gov/doc/dihedral_fourier.html
https://lammps.sandia.gov/doc/dihedral_spherical.html
If you receive a message ("Unknown bond style"), you might have to
compile a version of LAMMPS with the "class2" and "user-misc"
packages:
https://lammps.sandia.gov/doc/Build_package.html
https://lammps.sandia.gov/doc/Packages_details.html

unfortunately, it seems that I cannot use the same bond style twice.

LAMMPS will not complain if you define multiple bonds (and multiple
3-body angle and 4-body dihedral) interactions between the same atoms,
and you can use different parameters each time. (This is the reason I
replied to the thread.) However that's not a good idea. What Steve
suggested is much more efficient.

Andrew