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