Eur. Phys. J. D (2013) 67: 239
https://doi.org/10.1140/epjd/e2013-40319-7

Regular Article

Theoretical study of neutral bismuth-copper, bismuth-silver and bismuth-gold clusters

Instituto en Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado. Postal 70-360, C.P. 04510, México, D.F., Mexico

^a e-mail: sansores@unam.mx

Received: 24 May 2013
Received in final form: 6 September 2013
Published online: 22 November 2013

Abstract

The study of alloy clusters is particularly interesting since the importance of the electronic and geometrical contributions to the stability can be investigated by examining the influences of substituting different atoms in a cluster. In this work we study the equilibrium geometries, relative stability, and electronic properties including the ionization energy (IE), electron affinity (EA), reactivity, aromaticity, and gap of small Bi_mCu_n(bismuth/copper) clusters and their cations with m + n  5. The work is complemented with the study of small neutral bismuth/silver (Bi_mAg_n) and bismuth/gold (Bi_mAu_n) clusters. The study was done using density functional theory with the M06l functional. Comparison of neutral Bi_mCu_n clusters with the cationic Bi_mCu_n⁺ and neutral Bi_mAg_n and Bi_mAu_n clusters show only small distortions of the geometries, except for Bi₂Cu₂⁺, Bi₁Cu₄⁺, Bi₂Cu₃⁺, Bi₃Cu₂⁺, Bi₄Cu₁⁺, Bi₂Ag₂, Bi₃Ag, Bi₃Ag₂, Bi₂Ag₃, Bi₂Au₂, Bi₃Au and Bi₂Au₃. Our results on stability for cationic Bi_mCu_n⁺ clusters are consistent with experimental report. The electronic affinity for odd number of total atoms of Bi_mCu_n, Bi_mAg_n and Bi_mAu_n increases with increasing number of copper, silver or gold atoms. Moreover, it is found that the Bi_mAu_n are more stable than Bi_mCu_n and Bi_mAg_n structures. Nuclear independent chemical shift analysis confirms the presence of sigma and pi aromatic/antiaromatic character.