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

摘要

The structures, electron affinities, and dissociation energies of Asn/Asn- (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 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 Asn- clusters tend to be derived from the ground state structure of As_7 by adding As_((n-7)) species. The reliable AEAs (VDEs) of As_n 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 As_n, but not for VDEs. The dissociation energies (DEs) of arsenic atom from neutral As_n 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 Asn- (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.