Study of the compressibility of metal cyanamides and the pressure effect on their electronic properties

Based on the density functional theory, the effect of pressure on the structure and electronic properties of crystalline metal cyanamides Zn(CN$_2$) and NaSc(СN$_2$)$_2$ has been studied. The negative linear compressibility of Zn(CN$_2$) was revealed and its correlation with microscopic changes in the atomic structure under pressure was established. It is shown that NaSc(СN$_2$)$_2$ has a low compressibility (0.2 TPa$^{-1}$) in a direction close to that of cyanamide anions. Based on the quantum topological analysis of the electron density, interatomic interactions were studied and it was found that the Zn-N and Sc-N bonds have a partially covalent character. The band gaps of Zn(CN$_2$) and NaSc(СN$_2$)$_2$ at pressures up to 1 GPa have been determined and found to correspond to the UV range of 224–271 nm.