Modeling and simulating behavior of a transistor are described. At least one sub-circuit model for modeling at least one second order effect associated with the transistor is obtained. At least one instance parameter for the at least one second order effect is obtained. Operation of a transistor behavior simulator is augmented with the at least one sub-circuit model populated with the at least one instance parameter such that the simulating of the behavior of the transistor produces data that takes into account the at least one second order effect. The at least one second order effect may be an LOD/eSiGe effect, a poly pitch effect, or a DSL boundary effect. Also described is a method for generation of a sub-circuit model.