I 2D Ising Model Average Number of Domain Walls

  • I
  • Thread starter Thread starter thatboi
  • Start date Start date
  • Tags Tags
    Classical Domain
AI Thread Summary
The discussion centers on the classical Ising model on a 2-D square lattice with no external field, focusing on the average internal energy per site at criticality, which is calculated to be u = -√2 when the coupling constant J is set to 1. The query involves determining the average number of domain walls per site, given that each domain wall contributes an energy of 2. The ground state energy is established as -2N, and the goal is to find the number of domain walls needed to raise the energy to -√2N. The derived equation, n_walls/N = (2 - √2)/2, is proposed as a solution to this energy transition. The logic and calculations presented appear to be sound and consistent with the principles of the Ising model.
thatboi
Messages
130
Reaction score
20
Hi all,
I'm trying to see if my question/logic makes sense. Suppose I have a classical Ising model on a 2-D Square lattice with ##N## sites and 0 external field. There is an exact formula for the average internal energy per site, and at criticality it turns out to be ##u = -\sqrt{2}## where I have set the coupling constant ##J=1##. From here, I'd like to know if it is possible to find the average number of domain walls per site. I know each domain wall contributes energy ##2##. Now suppose the system is in its ground state (say all spin-up). Then the ground state energy is ##-2N##. I want to put in domain walls until the system energy increases to ##-\sqrt{2}N##, so we just need to solve ##-2N + 2n_{\text{walls}} = -\sqrt{2}N## and I get ##\frac{n_{\text{walls}}}{N} = \frac{2-\sqrt{2}}{2}##. Does this make sense?
 
Thread 'Gauss' law seems to imply instantaneous electric field'
Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
Hello! Let's say I have a cavity resonant at 10 GHz with a Q factor of 1000. Given the Lorentzian shape of the cavity, I can also drive the cavity at, say 100 MHz. Of course the response will be very very weak, but non-zero given that the Loretzian shape never really reaches zero. I am trying to understand how are the magnetic and electric field distributions of the field at 100 MHz relative to the ones at 10 GHz? In particular, if inside the cavity I have some structure, such as 2 plates...
Back
Top