Molecular Manipulation (object) – The ability to mentally manipulate the molecules of objects on a molecular level. A person with this power could turn a bullet into flowers.
Firestorm (DC) also has this power as well as a lot of stock superpowers (DC Who’s Who V1 #8).
Molecule Man (Marvel) has this power but on a large scale than Firestorm.
Atom Bob (Malibu) can transform energy and matter at the atomic level in the Ultraverse (1993 SkyBox Ultraverse).