Electron Affinity of Al₁₃: A Correlated Electronic Structure Study

Abstract

Neutral and anionic 13-atom aluminum clusters are studied with high-level, fully ab initio methods: secondorder perturbation theory (MP2) and coupled cluster theory with singles, doubles, and perturbative triples (CCSD(T)). Energies and vibrational frequencies are reported for icosahedral and decahedral isomers, and are compared with density functional theory results. At the MP2 level of theory, with all of the basis sets employed, the icosahedral structure is energetically favored over the decahedral structure for both the neutral and anionic Al13 clusters. Hessian calculations imply that only the icosahedral structures are potential energy minima. The CCSD(T)/aug-cc-pVTZ adiabatic electron affinity of Al13 is found to be 3.57 eV, in excellent agreement with experiment. ABSTRACT: Neutral and anionic 13-atom aluminum clusters are studied with high-level, fully ab initio methods: second-order perturbation theory (MP2) and coupled cluster theory with singles, doubles, and perturbative triples (CCSD(T)). Energies and vibrational frequencies are reported for icosahedral and decahedral isomers, and are compared with density functional theory results. At the MP2 level of theory, with all of the basis sets employed, the icosahedral structure is energetically favored over the decahedral structure for both the neutral and anionic Al 13 clusters. Hessian calculations imply that only the icosahedral structures are potential energy minima. The CCSD(T)/ aug-cc-pVTZ adiabatic electron affinity of Al 13 is found to be 3.57 eV, in excellent agreement with experiment.

Density Functional Theory Studies of the Extent of Hole Delocalization in One-Electron Oxidized Adenine and Guanine Base Stacks

“…This is a normal consequence of geometries optimized under constraints, i.e., in this case the B-DNA conformation. Imposing constraints on a structure to retain a specific conformation or symmetry usually results in small negative frequencies as reported by Smith and Gordon 55 for the calculation of neutral and anionic clusters of Al 13 . Though these (A 2 , A 2 •+ , A 8 and A 8 •+ ) have small negative frequencies, the overall features of these spectra are similar to those computed with fully optimized A 2 and A 2 •+ , see Figures 6 and S12.…”

“…34 This delocalized nature of hole distribution is supported from several experimental and theoretical efforts. 7,8,26,28,29,33,48,55 – 57 These calculations were done for gas phase systems and lack the environmental effects such as hydrogen bonding and solvent induced polarization which further affect the hole delocalization in A-stacks. However, our earlier study 34 on adenine dimer radical cation in the presence of several water molecules showed that spins were still delocalized in the ratio 73% and 27%.…”

Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

“…[40][41][42][43][44][45][46] It includes also a number of theoretical studies on the structural aspects of Al clusters, [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] and about their interaction [65][66][67][68][69][70][71][72] and reaction [73][74][75][76][77][78][79] with simple molecules.…”

DFT study on the structure and stability of Al13Bn±m clusters

“…This indicates that the spatial configurations of the clusters are influenced by the electronic arrangement. 31,32 The energy difference between the lowest-energy and low-lying structures (ΔE) and the Al-B bond length (R Al-B ) of Al 13 B n ±m (n = 1-6 and m = 0, 1) clusters are listed in Table II. Overall, the shortest Al-B bond length is 1.971 Å, and the longest Al-B bond length is around 2.690 Å for Al 13 B n ±m clusters.…”