Damour-Ruffini method and nonthermal Hawking radiation from Reissner-Nordstrom black hole

Taking into consideration the self-gravitational interaction and energy conservation, Hawking radiation from Reissner-Nordstrom black hole is re-investigated using the Damour-Ruffini method. It is found that the radiation is not exactly thermal, and the non-thermal Hawking radiation can carry information from the black hole. This can be used to explain the black hole information paradox, and the process satisfies the unitary thoery. A new method to calculate the corrected non-thermal Hawking radiation is given, which is more general. It can be used to study not only both the scalar field and Dirac field, but also massive and massless particle radiations.