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Colloidal Chemistry: Repulsion between two micelles (DLVO theory)

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NotSureReally:
I am trying to calculate the distance between two micelles in which potential switches from attractive to repulsive in water.


I been given the following information [also attached].

* Hydrophobic chain-water interfacial energy 
* Hamaker Constant
* Interaction constant
* Debye Length


My approach is to plot the curve of overall potential against distance by using DLVO theory:
net potential = attractive potential + repulsive potential
Vn = VA + VR

Then read distance off x axis at turning point from the curve.


I have the information and equation to calculate the potential of the attractive forces, but I can't seem to figure out how to calculate the repulsive forces from the given information. I was trying with the  Debye-Hückel approximation:

VR = Ψ0 exp-KD

I have K, but I'm unsure how to find Ψ0.

There is also another equation where repulsive energy between two spheres of radius R can be calculated:
VR = (64*n0*KBT*pi*R* γ2*e-KD) / K 2

but it involves parameters: reduced surface potential (γ) & ionic concentration in the bulk solution (n0).

Which are two things not directly given in the question, is it possible to somehow calculate these two things?
Is there another equation I can use to do this?

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