Ordinary field‐theoretic methods for self‐consistent wave functions which describe bond formation and dissociation. III. The commutative coupling approximation

The commutative coupling approximation of Hartree–Bogoliubov–Valatin theory is realized when the number‐conserving renormalized one‐body and number‐nonconserving pairing operators are assumed to commute. In this case, a set of self‐consistent one‐particle equations which involves a single operator may be solved. The commutative coupling approximations and the exact solutions are compared here for the fragmentation of LiH and FH. The results suggest that the commutative coupling approximation provides a useful zeroth‐order representation of fragmentation, and hence will induce suitable vacuua for applications' of Nambu's spinor representation of Feynman–Dyson–Goldstone diagrammatic perturbation theory to the problem of bond formation and dissociation.