Arsenic clusters Asn (n=6-16) and their anions: Structures, thermochemistry, and electron affinities

The structures, electron affinities, and dissociation energies of As-n/As-n(-); (n = 6-16) clusters have been examined by means of the B3LYP method. The basis set used in this examination is that of double-c plus polarization quality with additional diffuse s-, p-, and d-functions, designated as DZP++. Two different types of energy separation reported in this work are the adiabatic electron affinities (AEAs) and vertical detachment energies (VDEs). The ground-state structures of neutral As-n (n = 9-16) and their anions, with the exception of neutral As-10, can be regarded as being derived from the ground-state structure of As-7 (or As-8) by attaching As(n-7) (or As(n-8)) species. And the odd-numbered As; clusters tend to be derived from the ground state structure of As-7 by adding As(n-7) species. The reliable AEAs (VDEs) of Asn have been calculated to be 2.07 (2.18) eV for As-6, 2.68 (2.77) eV for As-7, 2.11 (3.09) eV for As-8, 2.80 (3.08) eV for As-9, 2.25 (2.51) eV for As-10, 2.80 (3.23) eV for As-11, 1.86 (2.11) eV for As-12, 2.92 (3.02) eV for As-13, 1.84 (2.16) eV for As-14, 3.02 (3.10) eV for As-15, and 2.13 (3.00) eV for As-16. There are odd-even alternations for AEAs as a function of size of Asn, but not for VDEs. The dissociation energies (DES) of arsenic atom from neutral Asn and their anions have been predicted to examine their relative stabilities. The results revealed that the even-numbered neutral As-n species are more stable than the odd-numbered clusters, and that the even-numbered anionic As-n(-) (n >= 4) species are less stable than the odd-numbered species. In addition, the reliable bonding energies per atom (BEPA) of As-n have been calculated. (C) 2013 Elsevier B.V. All rights reserved.