# Time-dependent external potential/force

Hello all!

I am writing my Master-Thesis at the moment. For this I would like to do some (very simple) simulations. I think MD should be the right thing. Essentially what I need is a free gas of particles confined in a box with reflecting walls (no interaction between gas particles). As I understand that should be not a big deal.
In addition to that I would also like to sweep e.g. with a step-potential through the volume. Or in other words; I need an external potential that is time-dependent and thus moves through the volume finally filling it completely (the position changes not the height/strength).
Is it possible to configure such a potential, or would I have to create a wall (may be out of very heavy particles) that produces this potential and then move this wall slowly? Can somebody point me into the right direction?

Thanks a lot for any replies, ideas, hints or solutions!
Greetings

ps.: I attached what I did so far - but it is not complete at all...

in.ucn (2.06 KB)

Ursin

Hello all!

I am writing my Master-Thesis at the moment. For this I would like to do some (very simple) simulations. I think MD should be the right thing. Essentially what I need is a free gas of particles confined in a box with reflecting walls (no interaction between gas particles). As I understand that should be not a big deal.
In addition to that I would also like to sweep e.g. with a step-potential through the volume. Or in other words; I need an external potential that is time-dependent and thus moves through the volume finally filling it completely (the position changes not the height/strength).

Could you clarify here a bit more? How are your particles expected to
interact with that potential? For example, an electrostatic potential
that is time dependent but has no spatial dependency will not create
any forces on charged particles as there will be no potential gradient
whatsoever at all times (zero electric field). Same with a
gravitational field. The fields are generally defined as gradients of
the potential thus you need to have some spatial dependency
added. But maybe what you call potential is the field already and you
just don't know the difference between them.
Carlos