A multiphonon-assisted model included in a Poisson-Schroedinger solver has been applied for the calculation of the capture/emission trapping rates of Si/SiO2 interface defects and their dependence with respect to the trap energy and depth in the oxide. The accurate trap cross-sections extracted with this approach permit compact modeling engineers to evaluate the accuracy of constant cross-section models. The model has been applied to extract the trap concentration and frequency response, comparing AC simulations with measurements. © 2011 IEEE.