I am trying to solve a nonlinear differential equation using NDSolve
numericaldiffeqqa =
NDSolve[{(q^\[Prime]\[Prime])[\[Phi]] + q[\[Phi]] == -(
1/(1 + q[\[Phi]])^2), q[0] == 1, q'[0] == 1},
q, {\[Phi], 0, 50}];
Plot[Evaluate[q[\[Phi]] /. numericaldiffeqqa], {\[Phi], 0, 50},
PlotRange -> All]
ParametricPlot[
Evaluate[{q[\[Phi]], q'[\[Phi]]} /. numericaldiffeqqa], {\[Phi], 0,
50}]
gives the result of
NDSolve::ndsz: At \[Phi] == 2.5326866484431907`, step size is effectively zero; singularity or stiff system suspected.
What do I do to fix this?