Vdwdefine changes the VDW radii of the specified atoms. If a plus (+) or minus (–) sign precedes value, the radii are increased or decreased, respectively, by value angstroms; otherwise, the radii are set to value angstroms. There should not be any space between the plus or minus sign and value.
~Vdwdefine restores the VDW radii of the of the specified atoms to their default values. The defaults depend on whether explicit hydrogen atoms are present; thus, the VDW radius of an atom may change when hydrogens are added or deleted.
vdwdefine 2.0 @c=- assign a radius of 2.0 Å to all atoms whose names begin with C
vdwdefine -0.5 :gly@ca- decrease the radii of glycine CA atoms by 0.5 Å
See also: vdw, vdwdensity, changing VDW radii