| The paper considers a discrete nano-crystalline model with complex crystal lattices. There are non close-packed lattices, typical for some metals and for solids with covalent bonds, for example, diamond, graphite. Traditionally to describe this kind of lattices one used many-particle-interaction potentials. The alternative approach considers rotational degree of freedom and allows the moment contribution in interatomic interaction. The particles interact, using forces and moments. In this paper the characteristics of interatomic bonds are determined for crystals with diamond structure (carbon, silicon, and germanium). It is shown that relation of bending stiffness of carbon covalent bonds to longitudinal one is between 0.49 0.72 (in diamond crystals). Hence, the bending stiffness is comparable with longitudinal, and it should be taken into account on calculation for covalent crystals. For crystals of silicon and germanium, this relation is equal 0.34. The strength of covalent bonds decreases with the rise of interatomic distance in sequence C-Si-Ge. |
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