function set_contour_data(E)

global energy_contour

step = .05;
x = -1.5 : step : 2;
y = -0.7 : step : 1.3;

xx = ones(size(y))'*x;
yy = y'*ones(size(x));
V = delfi(xx,yy);

ctrdata = contourc(x,y, V, [E E]);
energy_contour = ctrdata(:,2:(ctrdata(2,1)+1));
