king-probe 2.16.160404+git20180613.a09b012-1 (amd64 binary) in ubuntu focal

 king-probe is a program that allows one to evaluate atomic packing, either
 within or between molecules. It generates "contact dots" where
 atoms are in close contact.
 .
 The program king-probe generates "contact dots" at points on the van der
 Waals surface of atoms which are in close proximity to other atoms; reading
 atomic coordinates in protein databank (PDB) format files and writing
 color-coded dot lists (spikes where atoms clash) for inclusion in a
 kinemage.