Electron affinity of Al13: a correlated electronic structure study

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Aluminum clusters are of interest due to their unique electronic and structural properties.
• Understanding the stability of different isomers is crucial for predicting cluster behavior.

Purpose of the Study:

• To determine the preferred geometric structure of neutral and anionic 13-atom aluminum clusters (Al13).
• To compute and compare the energies and vibrational frequencies of icosahedral and decahedral Al13 isomers.
• To calculate the adiabatic electron affinity of Al13 and compare it with experimental data.

Main Methods:

• High-level ab initio methods, including second-order Møller–Plesset perturbation theory (MP2) and coupled cluster theory with singles, doubles, and perturbative triples (CCSD(T)).
• Comparison of results with density functional theory (DFT) calculations.
• Hessian calculations to confirm potential energy minima.

Main Results:

• The icosahedral structure was found to be energetically favored over the decahedral structure for both neutral and anionic Al13 clusters at the MP2 level.
• Hessian calculations indicated that only icosahedral structures represent stable potential energy minima.
• The calculated adiabatic electron affinity of Al13 using CCSD(T)/aug-cc-pVTZ was 3.57 eV, showing excellent agreement with experimental values.

Conclusions:

• The icosahedral structure is the most stable isomer for Al13 clusters.
• Computational results support experimental findings for the electron affinity of Al13.
• High-level ab initio methods provide accurate predictions for aluminum cluster properties.