We present calibration results for physically-based Compact Model Zero (CM0) used in OPC and OPC Verifications. The model sequentially solves equations for the exposure, baking, and development using 2D meshes and contour movements. CM0 can be used to explore next generation OPC techniques before CD calibration measurements are available, as well as an alternative to empirical compact models in routine OPC flows. Linearization of CM0 suggests modeling forms that are used in the CM1 model. CM1 is easier to calibrate because it is linear by the modeling coefficients and also includes modeling terms to account for long range loading effects.