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-ζ 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 Asn (n = 9–16) and their anions, with the exception of neutral As10, can be regarded as being derived from the ground-state structure of As7 (or As8) by attaching As(n−7) (or As(n−8)) species. And the odd-numbered As n - clusters tend to be derived from the ground state structure of As7 by adding As(n−7) species. The reliable AEAs (VDEs) of Asn have been calculated to be 2.07 (2.18) eV for As6, 2.68 (2.77) eV for As7, 2.11 (3.09) eV for As8, 2.80 (3.08) eV for As9, 2.25 (2.51) eV for As10, 2.80 (3.23) eV for As11, 1.86 (2.11) eV for As12, 2.92 (3.02) eV for As13, 1.84 (2.16) eV for As14, 3.02 (3.10) eV for As15, and 2.13 (3.00) eV for As16. 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 Asn 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 Asn have been calculated.