  Gravitational fragmentation has been proposed as a mechanism for the
formation of giant planets in close orbits around solar-type stars. However, it
is debatable whether this mechanism can function in the inner regions (R<40 AU)
of real discs. We use a newly developed method for treating the energy equation
and the equation of state, which accounts for radiative transfer effects in SPH
simulations of circumstellar discs. The different chemical and internal states
of hydrogen and the properties of dust at different densities and temperatures
(ice coated dust grains at low temperatures, ice melting, dust sublimation) are
all taken into account by the new method.We present radiative hydrodynamic
simulations of the inner regions of massive circumstellar discs and examine two
cases: (i) a disc irradiated by a cool background radiation field
(T_bgr=10K)and (ii) a disc heated by radiation from its central star
(T_bgr~1/R). In neither case does the disc fragment: in the former because it
cannot cool fast enough and in the latter because it is not gravitationally
unstable. Our results (a) corroborate previous numerical results using
different treatments for the hydrodynamics and the radiative transfer, and (b)
confirm our own earlier analytic predictions. We conclude that disc
fragmentation is unlikely to be able to produce giant planets around solar-type
stars at radii <40 AU.
