Atomic Phonology is a theory constraining phonological rules and phonological components of grammars which has been developed largely by Daniel Dinnsen in a number of papers since 1978. The basic principles of Atomic Phonology are set out in the following quotation:

(1) The theory of atomic phonology maintains that all linguistic variation requiring distinctly varied formulations of phonological rules is predictable from a set of atomic rules and universal principles of grammar… Atomic rules are entirely independent rules of grammar which are presumed to be the most basic, most specific rules that can be motivated on empirical grounds… Atomic rules thus specify all the necessary initial conditions from which any correct variation on that process for any natural language can be predicted by universal principles. Non-atomic rules are dependent on atomic rules. The dependence on atomic rules derives from the requirement that non-atomic rules are all and only those rules which are complements of atomic rules or complements of their complements. The complement relation may be defined as follows: Two rules are complements… if just those commonly shared (identical) features in the structural descriptions of the two rules are sufficient to define precisely the same set of input relations defined by the two rules jointly (Dinnsen; 1979: 31).