Eur. Phys. J. D (2014) 68: 105
https://doi.org/10.1140/epjd/e2014-40814-3

Regular Article

Theoretical study of the structures, stabilities, and electronic properties of neutral and anionic Ca₂Si^λ_n (n = 1-8, λ = 0, +1) clusters^*

¹ Department of Physics, Nanyang Normal University, Nanyang 473061, P.R. China
² Department of Chemistry, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
³ State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, P.R. China

^a e-mail: palc@163.com

Received: 19 December 2013
Received in final form: 12 February 2014
Published online: 29 April 2014

Abstract

The structures, stabilities and electronic properties of neutral and cationic, calcium-doped, small silicon clusters Ca₂Si^λ_n (n = 1-8, λ = 0, +1) have been systematically investigated by using the density functional theory method at the B3LYP/6-311G (d) level. The results show that the ground state optimal structures of the cationic and neutral clusters favour the three-dimensional structures for n = 3−8 respectively, and that the cationic Ca₂Si_n⁺ clusters have the lowest-energy structures similar to those of neutral Ca₂Si_n clusters with the exception of Ca₂Si₆⁺. The main configurations of the Ca₂Si_n isomers are not affected by removal of an electron, but the order of their stability is reversed. Based on the optimised geometries, the averaged binding energy (E_b), fragmentation energy (E_f), second-order energy difference (Δ₂E), HOMO-LUMO energy gap (E_gap), adiabatic ionisation potential (AIP) and vertical ionisation potential (VIP) are analysed for the most stable structures. We found that Ca₂Si₅, Ca₂Si₇ and Ca₂Si₇⁺ clusters have the strongest relative stability, and that the positive charged clusters are more stable than the corresponding neutral ones.