Recently I have been using geant4 to calculate the movement of low-energy electrons and positrons (eV -level) in materials. I found that electrons and positrons has interact when their energies are above 100eV, but when the energies are below 100eV, they do not interact, but directly become zero (that is, their energies do not have tens of eV states). I used SetUserLimits to set the minimum energy to 0.1eV and selected the electromagnetic process to G4EmStandardPhysics_option4. I don't know if I chose the wrong physical process, or if the set energy truncation is not effective, or if geant4 can't calculate the interaction process of electrons and positrons with energies less than 100eV.