  On the basis of ab-initio simulations, the value of strength of interatomic
bonds in one-, two- and three-dimensional carbon crystals is obtained. It is
shown that decreasing in dimensionality of crystal gives rise to nearly linear
increase in strength of atomic bonds. It is ascertained that growth of strength
of the crystal with a decrease in it dimensionality is due to both a reduction
in coordination number of atom and increase in the angle between the directions
of atomic bonds. Based on these data, it is substantiated that the
one-dimensional crystals have maximum strength, and strength of carbyne is the
absolute upper limit of strength of materials
