Custom Ticks in 2D Plot

Question

I'm having trouble customizing the ticks on a 2D plot.

I currently have:

Plot[{1/8(4-4x/(5.2917721067*10^(-11))-x^2/(5.2917721067*10^(-11)^2))\
e^(-x/5.2917721067*10^(-11))}, {x,0,15*5.2917721067*10^(-11)}]

I want to customize the ticks such that it shows a tick at every interval of a₀ = 5.2917721067*10^(-11) (hence the 0 -> 15*a₀).

However, when I try to do:

Plot[{1/8(4-4x/(5.2917721067*10^(-11))-x^2/(5.2917721067*10^(-11)^2))\
e^(-x/5.2917721067*10^(-11))}, {x,0,5.2917721067*10^(-11)}, Ticks -> 
{{5.2917721067*10^(-11), a0}, {2*5.2917721067*10^(-11), 2a0}...}]

It fails to even plot the correct graph; it attempts to plot a straight line defined by:

Plot 5.2917721067

Is there something I'm missing?

Answer 1

You had a number of syntax mistakes in the function you were plotting. Here's what I'd do in this case:

a0 = QuantityMagnitude[UnitConvert[Quantity[1, "BohrRadius"]]];
Plot[1/8 (4 - 4 x/a0 - (x/a0)^2) Exp[-x/a0], {x, 0, 15 a0}, 
     Ticks -> {Table[{k a0, Style[If[k > 1, Row[{k, Subscript[a, 0]}], Subscript[a, 0]],
                                  Small]},
                     {k, 0, 15}], Automatic}]