Question about ReaxFF and SHAKE command

Dear LAMMPS users,
can i use the command shake with the force field reaxff??

Dear LAMMPS users,
can i use the command shake with the force field reaxff??

technically, it should be possible, but:

- you have to provide a topology file with suitably added bonds and angles
- you have to use special_bonds lj/coul 1 1 1
- it is hard to predict how well the charge equilibration will handle
this. parameterizations were done and tested without.
- it won't save you any time like it would for conventional force fields

axel.

Thank you Axel,
but the topology of system is just defined in ReaxFF??

2013/3/28 Axel Kohlmeyer <[email protected]…92…>

Thank you Axel,
but the topology of system is just defined in ReaxFF??

so what? a.

I want to say that, using ReaxFF, I do not have to provide the topology of the molecule because it is already integrated into the force field

2013/3/28 Axel Kohlmeyer <[email protected]>

I want to say that, using ReaxFF, I do not have to provide the topology of
the molecule because it is already integrated into the force field

but if you want to shake bonds, you have to declare which ones to
constrain and to what length (and similarly for angles), don't you?
anything else just doesn't make any sense. a.

There are no fixed topology bonds in ReaxFF.
I.e. bonds that persist forever. The whole point
of ReaxFF is to compute and alter the bond topology
as the simulation runs (reactions). Fix shake requires
permanent bonds. If you simply want to
hold restrain two atoms, as if they were bonded
with a spring, then look at fix restrain.

Steve

Ok thank you

2013/3/28 Steve Plimpton <[email protected]…24…>