The energy of interatomic interaction for crystals of elements of the carbon subgroup

Experimental data are used to obtain the parameters of the pair potential of interatomic interaction for elements of the carbon subgroup. It is demonstrated that the potential depth of covalent bond, determined from the bulk modulus, is approximately twice the value which follows from the crystal atomization energy. A conclusion is drawn that the bond between a pair of atoms within a crystal is double. However, these two bonds are not equal in magnitude. It is demonstrated that the difference in magnitude between these two bonds increases with the bond energy in the carbon subgroup series and defines the energy of attraction of valence electron to “its” ion. A characteristic feature of double bond is that, for breaking this bond, it is sufficient to break one (the weaker) of two bonds.