I am trying to solve a coupled system of first order equations using NDSolve given below. The initial points I gave are approximately zero but my plot for z22sol[t] doesn’t start from zero. How can I force/make Mathematica plot the solution from 0?. thank you.
\[Omega] = 2*\[Pi]*20; \[Delta] = 0; sol2 = NDSolve[{z1'[t] == z3[t], z2'[t] == z4[t], z3'[t] == -2 \[Delta] (2*z3[t] \[Minus] z4[t]) \[Minus] \[Omega]^2 (2*z1[t] \[Minus] z2[t]), z4'[t] == -2 \[Delta] (z4[t] \[Minus] z3[t]) \[Minus] \[Omega]^2 (z2[t] \[Minus] z1[t]), z1[0] == 4.143977220216965`*^-8, z2[0] == 4.143977220216965`*^-8, z3[0] == 0.9999604734336653`, z4[0] == 0.9999604734336653`}, {z1, z2, z3, z4}, {t, 1, 2}, StartingStepSize -> 0.00025]; C1 = Plot[z22sol[t], {t, 1.0, 2.0}, Frame -> True, FrameLabel -> {StyleForm["time (secs)"], StyleForm["Displacement (m)"]}, PlotRange -> {All, All}, PlotLabel -> "Displacement of Second Attached Atom", GridLines -> Automatic, ImageSize -> Large, Axes -> FullGraphics, PlotStyle -> Automatic, PlotTheme -> "Scientific"] 
