Thank you!

But I think I forgot something important when explaining my problem. The point is that I don't want that each value of x is with all the possible values of y. What I want is that for each value of x there is only a possible value of y, even if they are not the same values.

For example, now, with your code, I have this table:

{0, 250000000}, {0, 300000000}, {0, 350000000}, {0, 400000000},... (all the possible combinations of the point x1=0 with all the y points) {3150000000, 0}, {3150000000, 50000000}, {3150000000, 100000000},... (all the possible combinations of the point x2=3150000000 with all the y points)

And what i want is something like this:

{0, 0}, {250000000, 300000000}, {35000000, 350000000},...

Is there a way to get only the points (x1, y1), (x2, y2), ..., (xmax, ymax)?

That's what I have now:

Table[{x, y}, {x, 0, 3154209492, 50000000}, {y, 0, 5463251097, 
  50000000}]

hbar := UnitConvert[1 \[HBar], "Electronvolts" "Seconds"];
mass := ParticleData["Electron", "Mass"];
f[x_, y_] = (hbar^2)*(x^2 + y^2)/(2 mass) ;
mod[{x_, y_}] = Sqrt[x^2 + y^2];

pts = Flatten[
   Table[{x, y}, {x, 0, 3154209492, 50000000}, {y, 0, 5463251097, 
     50000000}]];
fpts = f /@ pts;
modpts = mod /@ pts;

ListPlot[Transpose[{modpts, fpts}]]