Source code for siman.monte_functions

import os, subprocess
import math
import numpy as np
import copy
import datetime
import shutil
import traceback
import glob
from random import randint, random

from siman.header import printlog, kB






def metropolis(E1, E2, T = 1):
    """
    Metropolis algorithm
    """
    decrease = False # energy reduction
    
    # kB = 1.3806488*10**-23  / 1.6 * 10 **19
    dE = E2 - E1
    
    printlog("metropolis(): dE is ", dE)
    r = random()
    # printlog(-dE,kB,T)
    small = -0.000001
    if dE > small:
        e = math.exp(-dE/kB/T)
        printlog("exponent is  ", e)
        printlog("random number is ", r)
    else:
        e = 0.9999999
        
    if dE < small:
        printlog( "dE is ", dE, "Accept!")
        decrease = True
    elif  1 > e > r:
        printlog ("Accepted due to the temperature; exponent is ", e )
        decrease = True
    else:
        printlog('Not accepted')

    return decrease