Bonding.

In this paper, the bonding, relative stabilities and local ionic charges occurring in sodium chloride nanotubes are discussed. A new methodology is introduced which employs a linear relationship between nanotube cohesive energies determined via Density Functional Theory (DFT) and weighted-average Madelung Constants (MC(wa)). The slope of the linear plots reveals ionic charges and gives insights into ionic and other contributions to the bonding. Comparisons between ionic and cohesive bonding energies indicate that, as the nanotubes become longer, ionic bonding provides the principal contribution to the increased stabilization. Furthermore, comparisons between the total cohesive and electrostatic energies are used to calculate the percent ionicities. The nanotubes discussed in this paper show percent ionicity ranges from 47 to 58 %. Increasing lengths and decreasing widths of the tubes favor higher ionic character. A linear relationship linking the average ionic coordination number and MC(wa) is also presented for the first time.