Question of MC Simulation for XY Model - Comp-phys-alps-users

13 Oct 2020


      Hi,
I am just new to ALPS, and I have a question about running MC simulations of XY model:
Following the tutorials, I use python to run the simulations and change the model from “Ising” to “XY”, like:
...
import pyalps
parms = [
      {
          'LATTICE': "square lattice",
          'T': 1,
          'J': 1,
          'THERMALIZATION': 10000,
          'SWEEPS': 400000,
          'UPDATE': "cluster",
          'MODEL': "XY",
          'L': 8
      }
   ]
input_file = pyalps.writeInputFiles('data/parmXY', parms)
pyalps.runApplication('spinmc', input_file, Tmin=5)
result_files = pyalps.getResultFiles(prefix='data/parmXY')
data = pyalps.loadMeasurements(result_files)
how can I get some quantities like $$<M_x^2>=<\cos^2\theta>$$, or the nematic $$<N_x>=<\cos 2\theta>$$, where $$\theta$$ is the direction of the spin at each site? Is it possible to get these quantities I want through ALPS?
Really hope someone can give me a hint to do this. Thank you in advance!
Best,
Wei