Where can I find atomic charges and atom type informations COMPASS and DREIDING force field

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1

Dear Lammps users,

I would like to simulate polymer using COMPASS or DREIDING force fields. I prepared lammps data file using topotools, and I would like to assign my atom types, charges, bonding, dihedrals, and so on. Where I can find detailed information about COMPASS or DREIDING FFs?

Best regards,

Bat

2

Dear Lammps users,

I would like to simulate polymer using COMPASS or DREIDING force fields. I prepared lammps data file using topotools, and I would like to assign my atom types, charges, bonding, dihedrals, and so on. Where I can find detailed information about COMPASS or DREIDING FFs?

in the corresponding publications, of course.

axel.

3

Dear Axel,

Thank you very much for your prompt reply. I am very novice in LAMMPS. I am sorry for further asking.
I would like to use tersoff potential with one of those force fields (COMPASS and DREIDING).
Is it possible to use? I mean that should I use “pair_style hybrid”?

Best regards,

Bat

Dear Lammps users,

I would like to simulate polymer using COMPASS or DREIDING force fields. I prepared lammps data file using topotools, and I would like to assign my atom types, charges, bonding, dihedrals, and so on. Where I can find detailed information about COMPASS or DREIDING FFs?

in the corresponding publications, of course.

axel.

4

If you are new, then I would recommend against it. Mixing force fields is always a tricky issue and should be avoided, if possible.

While many combinations of force fields and settings are technically possible with pair style hybrid, only some of them produce meaningful results. others are of questionable quality or outright bad. Which is which cannot be said up front and in general. It is very system dependent and dependent on the kind of answer you are trying to extract from your simulations. Note that having parameters for each part of your system is not sufficient, but you also need parameters for the tersoff to non-tersoff interactions and those have to be of a pair-wise additive force field kind.

There are many previous discussions about the requirements and what can go wrong with pair style hybrid in the mailing list archives.

Bottom line, using hybrid force fields is a “advanced” topic and should thus only be used people with sufficient experience (or people that don’t mind wasting their time or publishing bogus results).

Axel.