First of all, you should add the underscores in the function definition:
pend[\[Theta]0_, \[Omega]0_, \[Gamma]_, \[CurlyPhi]0_, \[Omega]D_, T_]
Then you should insert a space or a multiplication sign between the two letters \[Gamma]\[Omega]. You also may consider using NDSolveValue instead of NDSolve, to get a simpler syntax.
