Density Functional Theory Study Of Alkaline-earth Metal Azides Clusters

Azide is a new type of high energy density material, metal azides as an important component of concern.But so far, the study of Alkaline-earth metal azides is still very limited. In this work, tructures and properties of azides (MN6)n(n=1～5,M=Ca,Mg) and (HMN3)n (n=1～5,M=Ca,Mg) clusters are studied by using the hybrid density functional theory (B3LYP) with 6-311G* basis sets.In chapter 2, we optimized the structures of the (CaN6)n(n=1～5) clusters, then the properties of the most stable isomers of these clusters were calculated. The calculated results show that azido in clusters has linear structure, the most optimized CaN6 has linear structure, and the most optimized (CaN6)n(n=2～5) clusters have chain structure; The Ca atoms show positive, the middle N atoms of azido show positive, and the N atoms at both ends of azido show negative; The IR spectra of the most optimized have four vibrational sections, the whole strongest vibrational peak lies in 2195～2280cm-1,and the vibrational mode is anti-symmetric stretching vibration of N-N bonds in azido. Stability analysis show that (CaN6)3 and (CaN6)5 clusters are more stable than other clusters.In chapter 3, we optimized the structures of the (MgN6)n(n=1～5) clusters, then the properties of the most stable isomers of these clusters were calculated. The calculated results show that azido in clusters has linear structure, the most optimized MgN6 has linear structure, the most optimized (MgN6)2 has four-membered ring planar structure of Mg2N2, and the most optimized (MgN6)n (n=3～5) clusters have chain structure; The Mg atoms show positive, the middle N atoms of azido show positive, and the N atoms at both ends of azido show negative; The IR spectra of the most optimized have four vibrational sections, the whole strongest vibrational peak lies in 2209～2313cm-1,and the vibrational mode is anti-symmetric stretching vibration of N-N bonds in azido. Stability analysis show that (MgN6)3 and (MgN6)5 clusters are more stable than other clusters.In chapter 4, we optimized the structures of the (HCaN3)n(n=1～5) clusters, then the properties of the most stable isomers of these clusters were calculated. The calculated results show that the most optimized HCaN3 has linear structure, and the most optimized (HCaN3)n (n=2～5) clusters have ring structure; The Ca atoms show positive, the H atoms show negative, the middle N atoms of azido show positive, and the N atoms at both ends of azido show negative; The IR spectra of the most optimized have four vibrational sections, the whole strongest vibrational peak lies in 2193～2302cm-1,and the vibrational mode is anti-symmetric stretching vibration of N-N bonds in azido. Stability analysis show that (HCaN3)3 is more stable than other clusters.In chapter 5, we optimized the structures of the (HMgN3)n(n=1～5) clusters, then the properties of the most stable isomers of these clusters were calculated. The calculated results show that the most optimized HMgN3 has linear structure, and the most optimized (HMgN3)n (n=2～5) clusters have ring structure; The Ca atoms show positive, the H atoms show negative, the middle N atoms of azido show positive, and the N atoms at both ends of azido show negative; The IR spectra of the most optimized have four vibrational sections, the whole strongest vibrational peak lies in 2219～2375cm-1,and the vibrational mode is anti-symmetric stretching vibration of N-N bonds in azido. Stability analysis show that (HMgN3)3 is more stable than other clusters.