# Kris's Research Notes

## January 17, 2011

### Droplet Experiments — Effect of Next-Nearest neighbor bonds

Filed under: GaAs Simulations — Kris Reyes @ 7:13 pm

We had briefly questioned whether adding next-nearest neighbor bonds would increase the droplet widths. The thought was that if these bonds existed within the droplet, we could control the geometry and perhaps force the droplets to be wider. Here are the results of one small run I did to test this. It turns out that increasing next-nearest bond strengths reduces the size of the droplets.

In this experiment, I fixed temperature $T = 464 K$, exact thickness $D = 2.92$ monolayers of Ga deposited at a rate of 0.1 monolayers/second. I varied droplet energy $\gamma = 0.29, 0.30, 0.35, 0.40$ eV and varied the next-nearest neighbor energy $\gamma^\prime = 0.25 \gamma, 0.5 \gamma$. Here are the autocorrelation functions (averaged over 16 trials) for each of the 8 combinations of $(\gamma, \gamma^\prime)$:

[gallery, exclude=”2872, 2878″ columns=”4″]

Here is droplet width as a function of $\gamma^\prime$:

Here is the number of droplets as a function of $\gamma^\prime$:

Therefore, by increasing next-nearest neighbor bond strength, we in fact create more, but smaller droplets.