Clearly, if the values between two or more atoms are markedly positive in the  def map, it indicates the formation of covalent interactions between them. Plotting a  def map is an ideal method for studying covalent interactions, as its physical meaning is clear, the map is easy to visually analyze, and it is applicable to the bonding between any elements. However,  def is currently less popular than ELF and LOL, mainly because only a few programs, such as Multiwfn, can conveniently plot it.