Hi Jack, I'm not using "atomic" here in an economic sense like the one you've described. It's not juxtaposed to cooperation or teamwork. Indeed, even the extreme egoist values cooperation and teamwork, albeit on radically different grounds than the most of us.
I use "atomic" here to describe a theory of identity. The opposite to this concept is "relational." It's a concept that describes how individuals define the "self." Atomism says, "I am who I am. What I do defines me. What others do is their business, it has nothing to do with me." On the other hand, relationalism says, "I am who society defines me to be. I have the power to define others insofar as others have the power to define me."
It's a difficult concept to differentiate indeed.