ELECTRODE Package Thomas-Fermi metallicity input parameters

I’m interested in using the Thomas-Fermi metallicity model in the ELECTRODE package and wanted to clarify what the voronoi parameter means. In the documentation, the command looks like

fix_modify ID tf type length voronoi

I understand what everything but the last parameter means. In the source code for the ELECTRODE package I found a reference to this as a reciprocal number density. How is the value calculated for a given electrode?

As an example, I’m trying to understand the choice in examples/PACKAGES/electrode/au-aq/in.tf. The system has gold fcc electrodes with lattice constant 4.07 Å and yields a voronoi value of 18.1715745. Any help understanding how to set this parameter would be very helpful, thank you!