1. Simulate an Ising model of length N=100 at temperature of temp=2.0 using the Metropolis algorithm at zero field. I suggest runs of length 100,000 Monte Carlo steps (where each step includes 1 attempted update per spin.)
2. Measure the fluctuation in the average magnetization, <m2>-<m>2 where m=(sum of spins)/N.
3. Add an applied magnetic field h and calculate the average magnetization <m> for field values h=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0.
4. Make a plot of <m> vs h and fit (by eye is fine) a straight line through the data for small h.
5. Compare the results. The slope of your graph is defined as the susceptibility Chi=dm/dh, and should have value Chi= (<m2>-<m>2 )N/temp. Do the two results agree?