Example of Wang-Landau for NH₃ adsorption : Monte Carlo method

Download test_wl_nh3-v3c2.py and NH3-V3C2 model

from susmost import *
from susmost import mc
import numpy as np

lt = load_lattice_task('models/nh3-v3c2', precission=1)
lt.set_ads_energy('nh3-atop-v3c2', -0.5)

T = 600.                        # arbitrary value - not used in Wang-Landau simulations
k_B = 0.000086          # Boltzmann constant, implies eV energy units
L = 12                          # Lattice size
m = mc.make_metropolis(lt, L, [T], k_B)
emin = -15.0    # minimal energy for Wang-Landau histogram
emax = 10.0             # maximal energy for Wang-Landau histogram
bincnt = 1000   # number of bins for Wang-Landau histogram

mc.wl_setup(m, emin, emax, bincnt)      # set Wang-Landau options

# do 100M Wang-Landau Monte Carlo sweeps without relaxation
mc.run(m, 100, 1000*1000, relaxation_steps=0, log_callback=lambda m: print (m.curE.sum()))

U_list = []
T_list = range(100, 1000+1, 10)
for T in T_list:
        a = mc.wl_analysis(m, T)
        U_list += [a.U]
        print ("Temperature = ", T)
        print ("Mean Energy = ", a.U)
        print ("Entropy = ", a.S)
        print ("Free energy = ", a.F)
        print ("Heat capacity = ", a.C)
        print ("\n")

import pylab as pl
pl.plot(T_list, U_list)
pl.show()