The Stark effect is produced when a static field alters molecular states. When the field applied is time dependent, the process is known as the dynamic Stark effect. Of particular interest for the control of molecular dynamics is the Non-Resonant Dynamic Stark Effect (NRDSE), in which the time dependent field is unable to effect a one-photon excitation. The intermediate strength laser pulse instead shapes the potential energy surfaces (PES) and so guides the evolution of the system. A prototype control scheme uses the NRDSE to change the topography of PES in regions where they intersect, thus providing control over photochemistry. Following earlier experimental work, in this paper we study the NRDSE on a new 3 state model of the IBr molecule to gain insight into the mechanism of control at the avoided crossing that governs the branching ratio of the photodissociation.