First principles study on small ZrAln and HfAln clusters: Structural, stability, electronic states and CO2 adsorption

Abstract

We report a first principles study based on density functional theory on the structural and electronic properties of transition metal Zr and Hf doped small aluminum clusters with 1 to 7 aluminum atoms. We have used B3PW91/LANL2DZ basis set in Gaussian 09 package. The stability analysis reveals that the ZrAl 4 and HfAl 4 structures with C 2 v symmetry and square pyramid geometry are lowest energy structures. The most stable structures in ZrAl 5 and HfAl 5 are distorted tetrahedron type structure with symmetry C 1 . The binding energies per atom for transition metal doped Al n clusters increases with the cluster size, while the second order difference in total energy show oscillatory behavior with even and odd cluster size. The HOMO -LUMO gap for ZrAl n is larger than the HfAl n clusters except for n = 1 and 3. The HfAl 6 has more tendency to accept or give away electrons. The negative charge exists on Zr and Hf indicating that the electron transfers from Al atom to transition metal, Zr and Hf. The thermodynamical analysis suggest that the HfAl 6 cluster has highest exothermicity compared to not only all considered Al clusters but also other transition metal doped Al clusters reported in J.Phys. Chem. C, 120, 10027 (2016).

Hydrogen evolution reaction between small-sized Zr n (n = 2–5) clusters and water based on density functional theory

“…All the calculations were performed with B3LYP functional based on density functional theory (DFT), which is a combination functional of Becke's three parameter exchange functional (B3) [30,31] with the Lee-Yang-Parr (LYP) [32] generalized gradient correction functional. The LANL2DZ [29,[33][34][35][36][37] basis set was used for Zr atoms, while the 6-311++G (3df, 3pd) [38] basis set was used for O and H atoms. To begin with, we performed optimization and frequency analysis of various isomers of Zr n (n = 2-5) clusters to determine the most stable structures.…”