controlling incidence angle in fix deposit and tracking sputter angles

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1

Hi all,

I am working on doing some work on sputtering using MD. Previous work of mine has all been normal incidence angles and worried only about yield rate. However, I am now looking at what happens when we change impact angle.

Questions are:

  • how to use fix deposit to change impact angle. I know I can use target to specify the area to hit, but isn’t the atom still coming from a region where it is randomly generated within the region? So how can I control the angle from the perpendicular z axis?

  • when sputtering often times experimental sputtering yields are less than 1. How can we achieve this? Given many times there is only 1 impact, I assume you would do several 1 off simulations with different positions and get a statistical average? As an alternative, would multiple impacts achieve the same?

  • How to track the polar coordinates of outgoing atoms.

Thanks very much.

Carly

2

If you set the vx,vy,vz params of fix deposit, that sets the initial
velocity of the impacting atom, and hence its incident angle.

To get good stats you can either deposit many atoms successively.
Or you can rerun a 1-impact simulation many times, using different
random #s. You can do the latter from one script by running
successive simulations and using variables in the input
script that change input values for each simulation. See
the variable doc page and Section 8.2.3 of the manual.

Steve