Cross terms in Dreiding force field

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1

Hello all,

I would like to use Dreiding Force Field to calculate BH4 groups. I have found the bond and angle terms that I need from the manual. In addition to this, there are another two corss terms (bond-bond corss term and angle-angle cross term) that I want to use. Ebond-bond=K(R1-R0)(R2-R0), Eangle-angle=K((cosθ1-cosθ)^2(cosθ2-cos****θ)^2. But I can’t find the two cross terms from bond_style and angle_style. Where I can find these two terms?

Thanks a lot in advance!

Best,

Hang

2

You can look at the pair style doc pages for the Dreiding implementation
in LAMMPS. I don't think it has any cross terms as yuu describe. You
can also look
at the class 2 bond/angle/etc doc pages which do include cross terms.
There's nothing stopping you using those with the Dreiding pair style
in LAMMPS if they are what you want. Perhaps Tod can comment
on the scope of what you are calling the Dreiding ff.

Steve