hbarc = 197.326;
mu = 4000.;
S0 = 3.0;
omega = 0.0001;
ec = 0.0854;
q = 2.*ec;
Q = 5.0;
V0 = 0.;
V1 = 20.;
a = 10.;
l = 5.;
x0 = 0.;
xN = a + l + 10.;
A0 = mu omega S0/(hbarc q);
k = Sqrt[2 mu Q]/hbarc;
potential[x_] = Piecewise[{{V1,a<=x<=a+l},{V0,x<a||x>a+l}};