Theoretical models implemented in the version 9.6.p02 of the Geant4 Monte Carlo simulation toolkit for the
total and differential cross sections for pion photo-production were validated against experimental data.
This presentation reports on the gamma p -> pi0 p reaction. Two models were studied: the Chiral Invariant
Phase Space (CHIPS) and Bertini (BERT). The experimental data are from the CEBAF Large Acceptance
Spectrometer (CLAS detector) of Jefferson Lab,the Scattering Analysis Interactive Dial-in (SAID) and the
world data (only for sigma_tot). The CHIPS model is the only one that can adequately reproduce the main
resonances for the reaction channel with a corrective coefficient needed to perform the result.