Transition-metal (TM)-doped boron clusters have received considerable attention in recent years, in part, because of their remarkable size-dependent structural and electronic properties. However, the structures of medium-sized boron clusters doped with TM atoms are still not well-known because of the much increased complexity of the potential surface as well as the rapid increase in the number of low-energy isomers, which are the challenges in cluster structural searches. Here, by means of an unbiased structure search, we systematically investigated the structural evolution of medium-sized tantalum-doped boron clusters, TaB (n = 10-20). The results revealed that TaB (n = 10-15) clusters adopt half-sandwich molecular geometries, with the notable exception of TaB, while for n = 16-18 and 19-20, the lowest-energy clusters are characterized by drum-type geometries and tubular molecules with two B atoms on the top, respectively. Good agreement between the calculated and experimental photoelectron spectra strongly support the validity of our global minimum structures. Molecular orbital and adaptive natural density partitioning analyses indicate that the enhanced stability of half-sandwich TaB is due to the strong interaction of the Ta atom (5d orbitals) with surrounding B atoms (2p orbitals) and σ B-B bonds in the B moiety.
Enormous
progress has been made in catalytic oxidation reactions
involving nanosized gold particles. However, the reaction mechanism
of O2 with neutral gold clusters remains complicated. Here,
we have performed an unbiased structure search for Au
n
Q
and Au
n
O2
Q
(n = 2–10, Q = 0, −1) clusters
by means of CALYPSO structure searching method. Subsequently, the
lowest-energy candidate structures were fully optimized at the B3PW91/Au/LANL2DZ/O/6-311+G(d)
level of theory to determine the global minimum structures. Based
on the ground-state structures of Au
n
– and Au
n
O2
– (n = 2–10), we have simulated
the photoelectron spectra (PES) using time-dependent density functional
theory. The good agreement between simulated PES and the corresponding
experimental data suggest that the current ground-state structures
are the true minima. The locally maximized value of the adsorption
energy in Au5O2, where the unpaired electron
of Au5 can transfer to O2, makes it the most
promising candidate of the chemisorbed complex. A comprehensive analysis
of molecular orbitals and chemical bonding of the Au5O2 cluster reveals that O2 can be chemisorbed onto
the neutral Au5 cluster.
In a Nash equilibrium, every participant's strategy is the optimal reaction to the strategies of others. Based on economic theory, this paper analyses core stakeholders' behaviour in the tourism community at Qingcheng Mountain, Chengdu, China. Taking taxation, land prices and employment as the payoffs, and the local government, the community and the investors as the players, the incomplete information static game model is applied to outline the stakeholders' behaviour. The paper also examines who benefits the most and who occupies a dominant position. The results indicate that the game strategy of residents in Qingcheng Mountain is influenced by the investors. The influence of the investors is also crucial in the decision making mechanism of the tourism community to maintain sustainable tourism development.
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