# Calculate The Distance Where Atoms Start to Repel Each other

1. Jul 19, 2015

### nst.john

Is there a way to calculate how close two atoms can get before their electrons start to repel each other and prevent atoms from getting closer together. I'm guessing this is dependent on the size of the atom and it's number of protons and electrons. I am asking because I am working on a sonoluminescence project and papers say that a sonoluminescent bubble reaches minimum size when the atoms in the bubble cannot be compressed anymore due to electron repulsion. So what I want to know is exactly how far is each atom from each other where the electron repulsion will stop the bubble from compressing further. Thank you!

2. Jul 20, 2015

### Staff: Mentor

There is no such thing as the "minimum distance". How close atoms will get to each other is a matter of a pressure applied. The higher the force pushing atoms to each other, the closer they get. Lennard-Jones potential (mentioned in most general chemistry books) describes this dependence. However, it requires two parameters - I guess they can be calculated using QM methods.

3. Jul 20, 2015

### cpsinkule

Are you talking about coulomb repulsion or Electron degeneracy?

4. Jul 20, 2015

### nst.john

What's the difference between the two?

5. Jul 20, 2015

### nst.john

And I'll look into the Lennard-Jones potential.

6. Jul 20, 2015

### cpsinkule

Coulomb potential is felt at all distances. Electron degeneracy pressure is what keeps two electrons occupying the same state

7. Jul 20, 2015

### nst.john

I'm guessing coulumb potential because it sounds like it would increase as two atoms got closer to each other, until it gets too great that they cannot get closer with the force applied due to electron repulsion