caffeine

The RasMol scripting language has two synonymous commands to control atom size, spacefill and cpk (for Corey, Pauling, and Koltun). The commands are aliases and run exactly the same code.

As an extension to the RasMol scripting language, Jmol allows you to specify your size as a percentage of the vanderWaals radius.

If you want to specify a fixed size then you can do so in Angstroms. Note that the last button specifies "1.0" instead of the integer "1". This is important because integer values specify RasMol units (1/250th Angstrom)