Monte Carlo Simulation, Ising model in 2D

[Firben]

Homework Statement

Lo,Im stuck on how to retrieve the specific heat capacity from an MC simulation, with the metropolis algorithm. I want my graph to look something like this:
https://i.stack.imgur.com/NXeXs.png

Homework Equations

C_v = ((<E^2>-<E>^2)/T^2

The Attempt at a Solution

My code is similar to this guy:

but without magnetization

To retrieve C_v i wrote the following code to 4:19 from the video above.

Cv = (E2/16384 - E.*E/16384^2)./(T(i).^2);

plot(T,Cv);Where E2 is given by the code:

function [E2] = ising_energy(u,J)

[L1,L2] = size(u);
E2=0;
for i=1:L1
for j=1:L2
f1i=mod(i,L1)+1;
f2j=mod(j,L2)+1;
forward_neighbors=u(f1i,j)+u(i,f2j);
E2=E2-(J*u(i,j)*forward_neighbors)*(J*u(i,j)*forward_neighbors);


end;clear j
end;clear i

However my graph looks more like the plot of <E> vs T.

 

[Firben]

No, I am still stuck atm. Cant get any reasonable graph. Is there someone that have done this type of simulation before ?

 

[Firben]

Someone that knows what iam missing ?

 

[MohammadJCM]

Someone that knows what iam missing ?

where is your code?

 

[Firben]

where is your code?

I solved it