docs: def get_ZPE(viblist):
      """Returns the zero point energy from a list of frequencies.
  
      Parameters
      ----------
      viblist : List of numbers or string of list of numbers.
  
      Returns
      -------
      ZPE : Zero point energy in eV.
      """
      if type(viblist) is str:
          l = ast.literal_eval(viblist)
      else:
          l = viblist
      l = [float(w) for w in l]
      ZPE = 0.5*sum(l)*cm2ev
      return(ZPE)