new_contents: import os
  import time
  import yaml
  import json
  import datetime
  import numpy as np
  import pandas as pd
  from time import strftime
  from pprint import pprint
  import matplotlib.pyplot as plt
  
  from diffpy.Structure import loadStructure
  from diffpy.Structure import StructureFormatError
  from diffpy.srreal.structureadapter import nosymmetry
  from diffpy.srreal.pdfcalculator import DebyePDFCalculator
  from diffpy.srreal.pdfcalculator import PDFCalculator
  
  from pdf_lib.glbl import pdfCal_cfg, Uiso, delta2
  
  cal = PDFCalculator()
  cal.delta2 = delta2
  ni = loadStructure('ni.cif')
  ni.Uisoequiv = Uiso
  nacl = loadStructure('1000041.cif')
  nacl.Uisoequiv = Uiso
  print("Uiso = {}".format(Uiso))
  
  
  def qdamp_test(struc, rmax_val, qdamp_array=None):
      pdfCal_cfg['rmax'] = rmax_val
      N = qdamp_array.size
      fig, ax = plt.subplots(N, figsize=(20, 6),
                             sharex=True, sharey=True)
      for _ax, qdamp_val in zip(ax, qdamp_array):
          pdfCal_cfg['qdamp'] = qdamp_val
          r, g = cal(struc, **pdfCal_cfg)
          #cal.setStructure(struc)
          #for k, v in pdfCal_cfg.items():
          #    setattr(cal, k, v)
          #cal.eval()
          #r = cal.rgrid
          #g = cal.pdf
          _ax.plot(r, g, linestyle='-',
                  label="{:.3f}".format(qdamp_val))
          _ax.legend()
      fig.suptitle('{}'.format(struc.composition))
      print(cal.rstep)
      print(cal.slope)
  
  qdamp_array = np.arange(0, 0.1, 0.02)
  rmax = 50.
  qdamp_test(ni, rmax, qdamp_array)
  qdamp_test(nacl, rmax, qdamp_array)
  
  
subject: add example of demonstrating qdamp effect