Molecular dynamics in intense fields. II. Adiabatic approximations and coupled equations

Electrons, nuclei, and photons are treated simultaneous quantum mechanically for molecular multiphoton processes. Coupled equations are derived for these processes in weak and intense electromagnetic fields. Different gauges are shown to give rise to different adiabatic separations for all three constituents. The Bloch Nordsieck transformation of QED which was applied in a previous paper is extended further and is discussed in relation to the other gauge representations.