set xlabel 'x (internal units)'
set ylabel 'psi(x)'
set term png
set out 'harmonic0.png'
p [-10:10][-1.5:1.5] '10_500_0.dat' u 1:2 index 0 lw 2 w l, '' u 1:2 index 1 lw 2  w l, '' u 1:2 index 2 lw 2 w l,f(x),'' u 1:5 index 0 lw 1 w l, 0