Interactions in chemical systems can be divided into two main categories: chemical bonds and weak interactions. Chemical bonds have a short interaction distance and usually have a large strength. They can generally be classified into covalent bonds (including coordination bonds and metallic bonds in specific situations) and ionic bonds, and the interaction energy is generally several hundred kJ/mol. Weak interactions have a much longer action distance and are about one order of magnitude weaker than chemical bonds. They contain a wide variety of types, such as ordinary van der Waals (vdW) interactions, hydrogen bonds (H-bonds), halogen bonds, chalcogen bonds, pnicogen bonds, tetrel bonds, dihydrogen bonds, regium bonds, - interactions, and their interaction energy is generally several to tens of kJ/mol. There are also some interactions between the two categories, such as the charged H-bond [FHF] -, which has a strong covalent nature with an interaction energy of as high as 274 kJ/mol. The interactions can also be divided into covalent interaction and noncovalent interaction according to their nature, the ionic bonds and weak interactions of common strength collectively correspond to the latter. Whether and where various interactions exist in a chemical system, and what the nature they are, are always the issues of greatest concern to chemists. Studying these interactions is not only of great theoretical significance, but also of important practical significance.