Class of solutions of the Wheeler-DeWitt equation in the   Friedmann-Robertson-Walker universe
  We show that the solutions of the Wheeler-DeWitt equation in a homogeneous and isotropic universe are given by triconfluent Heun functions for the spatially closed, flat, and open geometries of the Friedmann-Robertson-Walker universe filled with different forms of energy. In a matter-dominated universe, we find the polynomial solution and the energy density spectrum. In the cases of radiation-dominated and vacuum universes, there are no polynomial solutions as shown. 
H. S. Vieira, V. B. Bezerra
gr-qc math-ph math.MP