How to set the "vacuum_density "

[andyfan]

Dear Wenjie and graeme,

I saw the new bader code is available on the main page today. Thanks for updating the code.
I tried to use the new code in my system, and I found that the vacuum volume is very sensitive to the "vacuum_density " that I set. So I want to know is there any rules to set that value, or what about your suggestions?

Sincerely,

Fan

[chill]

I did some testing and it seems that the default value of 1e-3 electrons per Angstrom cubed is a reasonable value. However, there doesn't seem to be a perfect cutoff value for the charge density.

These plots show vacuum charge and vacuum volume as a function of the charge density cutoff. It is for a 111 slab in a box that is ~1800 A^3. One of the plots is over the entire range of charge density. It makes it easy to see when the charge density starts to cut into the atomic charges as the slope of the vacuum charge line gets very large. The other plot shows only small values of the vacuum cutoff. It looks likes .001 gets most of the vacuum volume without getting too much of the charge.