out of plane modes

Dear All,

Thank you very much for useful suggestions. I managed to get out of plane vibrations for atoms in Graphene using initial velocity.

Still I would like to know what does (free boundary condition) corresponds to in LAMMPS? Is it (f) or (s) or (m)?

People say they use periodic bc on x and y plane and free bc for out of plane direction. then use NPT or NVT before running NVE.

However NPT/NVt does not work with non-periodic BC.

I sincerely appreciate your helps to resolve my confusion.

Regards,

Daryoush

Dear All,

Thank you very much for useful suggestions. I managed to get out of plane
vibrations for atoms in Graphene using initial velocity.

Still I would like to know what does (free boundary condition) corresponds
to in LAMMPS? Is it (f) or (s) or (m)?

​unless you explain what exactly​ you understand under "free" boundary
condition, nobody will be able to answer.

People say they use periodic bc on x and y plane and free bc for out of
plane direction. then use NPT or NVT before running NVE.

if this is supposed to imply that "free" means "non-periodic, then​ *all*
of the​ three options listed above are non-periodic.

However NPT/NVt does not work with non-periodic BC.

​that is an incorrect statement. fix nvt works with *any* combination of
boundary ​conditions and fix npt can *also* be used on systems with
non-periodic boundaries for also long as the constant pressure
functionality is *only* coupled to periodic dimensions (as it doesn't make
sense for non-periodic boundaries).

axel.

Hello Axel,

Thank you for your help. If I knew exactly what the authors of 50+ papers that I perused mean by (free), then I could have found its lammps equivalent. I tested (f) (s) and (m) and I know what they do visually in OVITO at least.

I guess I have to ask those authors to see what they mean by (free). Thank you anyway.

Regards,

Daryoush