Negative linear compressibility from helix in zinc carbodiimide

Abstract

Zinc carbodiimide, Zn(CN₂), exhibits negative linear compressibility (NLC) along the c-axis under hydrostatic pressure. Density functional theory calculations indicate that at high pressure, the a- and b-axes shrink, while the infinite –Zn–N–C–N– helical chains elongate through inter-chain Zn–N bonds, leading to expansion of the crystal along the c-axis.