How to plot this equation

I'm trying to plot the figure below, but I don't really understand what function to use to achieve this.

β is defined as , where the T used is for low temperature

I tried using syms delta and fplot(@(delta) U) but that doesn't seem right.

[Matt J]

but that doesn't seem right.

Why not?

Answer 1

[Paul]

syms U Delta beta T k_beta
U = -Delta/2*tanh(beta*Delta/2)

U = 

UoverDelta = U/Delta

UoverDelta = 

UoverDelta = subs(UoverDelta,beta,inv(k_beta*T))

UoverDelta = 

syms w
UoverDelta = subs(UoverDelta,k_beta*T/Delta,w)

UoverDelta = 

figure
fplot(UoverDelta,[0 10])
ylim([-1 0])