- #1
JorisL
- 492
- 189
Hi
For a simulation regarding Lennard Jones fluids I'm getting divergences.
I have particles in a fixed volume.
I calculate distances between these particles to find the force.
However in the first iteration I already get divergences (NaN values in matlab).
I use [tex]F_x^{ij} = 24\varepsilon \left( 2r_{ij}^{-14}-r_{ij}^{-8}\right)\cdot \Delta x_{ij}[/tex]
Where the i,j have to do with the particles I'm viewing. For each direction I get such a force.
But some of the particles get so close that this force and hence the acceleration effectively become infinity. My simulation obviously breaks down at this point.
I tried changing the timestep, this doesn't do anything.
It worked at some point but I don't recall changing anything after that. Except adding the thermostat code which I can turn off. The divergence remains.
You can find my (messy) code in this pastebin http://pastebin.com/62v1yTCY
I've been looking at it for hours already yet I can't find any solution.
JorisL
Edit;
I had divergences before. Those were caused by an error in applying the periodic boundary conditions. I forgot using the nearest image convention at that time.
For a simulation regarding Lennard Jones fluids I'm getting divergences.
I have particles in a fixed volume.
I calculate distances between these particles to find the force.
However in the first iteration I already get divergences (NaN values in matlab).
I use [tex]F_x^{ij} = 24\varepsilon \left( 2r_{ij}^{-14}-r_{ij}^{-8}\right)\cdot \Delta x_{ij}[/tex]
Where the i,j have to do with the particles I'm viewing. For each direction I get such a force.
But some of the particles get so close that this force and hence the acceleration effectively become infinity. My simulation obviously breaks down at this point.
I tried changing the timestep, this doesn't do anything.
It worked at some point but I don't recall changing anything after that. Except adding the thermostat code which I can turn off. The divergence remains.
You can find my (messy) code in this pastebin http://pastebin.com/62v1yTCY
I've been looking at it for hours already yet I can't find any solution.
JorisL
Edit;
I had divergences before. Those were caused by an error in applying the periodic boundary conditions. I forgot using the nearest image convention at that time.
Last edited: