Thank you so much for your advice.
I’m not sure why 0.9346 MeV gamma-ray was generated, but all gamma-rays in the first table should have been generated from a single neutron capture of 58Ni.
In fact, this problem has recently been solved.
According to an expert of our research group, total energy of gamma-rays from a single neutron capture seems not to be conserved in default setting.
And this problem was resolved by setting the environment variable “G4NEUTRONHP_USE_ONLY_PHOTONEVAPORATION” before running Geant4.