  The existence of numerical solutions to a fourth order singular boundary
value problem arising in the theory of epitaxial growth is studied. An
iterative numerical method is applied on a second order nonlinear singular
boundary value problem which is the exact result of the reduction of this
fourth order singular boundary value problem. It turns out that the existence
or nonexistence of numerical solutions fully depends on the value of a
parameter. We show that numerical solutions exist for small positive values of
this parameter. For large positive values of the parameter, we find
nonexistence of solutions. We also observe existence of solutions for negative
values of the parameter and determine the range of parameter values which
separates existence and nonexistence of solutions. This parameter has a clear
physical meaning as it describes the rate at which new material is deposited
onto the system. This fact allows us to interpret the physical significance of
our results.
