The voidsizes are a measure for how evenly the atoms in a material are distributed. This is primarily of interest for amorphous materials, as the atoms are arranged in an irregular manner.
What you measure is essentially the volume of the void space between the atoms.
This volume is calculated by first creating a Delauney traingulation (
https://en.wikipedia.org/wiki/Delaunay_triangulation) of the atoms in the system, and then calculating the tetrahedral volume for each simplex. The size of a void is then calculated as the diameter (in Angstrom) of a sphere with equivalent volume.
The Voidsize Distribution analysis gives the distribution of these sizes in the system.
The Element selection lets you select only a subset of elements for whcih the voidsaize should be calculated, but the most common case would be that would calculate the voidsize for all elements in the system.
The Resolution selection lets you choose the bin size that is used when calculating the histogram of the void sizes.
