A reformulation of molecular quantum electrodynamics

A new gauge condition which leads directly to the 'multipole' hamiltonian for the interaction of molecules with the electromagnetic field is studied within the context of quantum electrodynamics ie when the molecules and field are considered as a closed dynamical system. The new formalism which maintains the advantages of the usual Coulomb gauge theory but avoids the difficulties associated with the presence of unphysical terms in the propagation function of the Coulomb gauge vector potential, is thus obtained without recourse to the unitary transformation of the usual Coulomb gauge formalism which has previously been used to achieve this result.