Minimal Theory of Isomerism -Q.Q and Other Interactions.

We perform shell model calculations using a quadrupole-quadrupole interaction (Q.Q) in single a j shell space. We show that this one-parameter interaction is a good predictor of where nuclear isomerism occurs and where it does not occur. The limitations of this interaction are also discussed. We then include other interactions e.g. in the f_{7/2} shell those obtained from the (local) spectrum of a 2 particle system and then from a 2 hole system. In the g_{9/2}where there is insufficient empirical data from the 2 hole system and so various empirical interactions are used.