Electronic and atomic structure of the Al(n)H(n+2) clusters

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Investigating the electronic and atomic structure of hydrogenated aluminum clusters is crucial for understanding their stability and properties.
• The family of hydrogenated aluminum clusters, denoted as Al(n)H(n+2) for n=4-11, presents a unique system for theoretical study.

Purpose of the Study:

• To explore the electronic and atomic structures of Al(n)H(n+2) clusters.
• To determine the chemical stability and electronic properties, including HOMO-LUMO gaps.
• To assess the applicability of the Wade-Mingos rule to these hydrogenated aluminum clusters.

Main Methods:

• Employed density functional theory (DFT) with the generalized gradient approximation (GGA) for exchange-correlation calculations.
• Calculated highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) gaps.
• Utilized time-dependent density functional theory (TD-DFT) to compute photoabsorption spectra.

Main Results:

• All studied Al(n)H(n+2) clusters possess substantial HOMO-LUMO gaps, indicating high chemical stability.
• The Al(6)H(8) cluster exhibits the largest HOMO-LUMO gap (2.81 eV).
• Five clusters (Al(4)H(6), Al(5)H(7), Al(6)H(8), Al(7)H(9), Al(10)H(12)) conform to the Wade-Mingos rule, featuring stable Al cages and terminal Al-H bonds.

Conclusions:

• Hydrogenated aluminum clusters satisfying the Wade-Mingos rule demonstrate superior chemical stability and wider electronic gaps.
• The electronic structure and stability trends correlate with calculated photoabsorption spectra.
• DFT and TD-DFT provide valuable insights into the properties of these hydrogenated aluminum clusters.