Structural and electronic properties of Aun−xPtx (n = 2–14; x ⩽ n) clusters: The density functional theory investigation

Abstract

The structural evolutions and electronic properties of bimetallic Aun–xPtx (n = 2–14; x ⩽ n) clusters are investigated by using the density functional theory (DFT) with the generalized gradient approximation (GGA). The monatomic doping Aun–1Pt clusters are emphasized and compared with the corresponding pristine Aun clusters. The results reveal that the planar configurations are favored for both Aun–1Pt and Aun clusters with size up to n = 13, and the former often employ the substitution patterns based on the structures of the latter. The most stable clusters are Au6 and Au6Pt, which adopt regular planar triangle (D3h) and hexagon-ring (D6h) structures and can be regarded as the preferential building units in designing large clusters. For Pt-rich bimetallic clusters, their structures can be obtained from the substitution of Pt atoms by Au atoms from the Ptn structures, where Pt atoms assemble together and occupy the center yet Au atoms prefer the apex positions showing a segregation effect. With respect to pristine Au clusters, AunPt clusters exhibit somewhat weaker and less pronounced odd-even oscillations in the highest occupied and lowest unoccupied molecular-orbital gaps (HOMO-LUMO gap), electron affinity (EA), and ionization potential (IP) due to the partially released electron pairing effect. The analyses of electronic structure indicate that Pt atoms in AuPt clusters would delocalize their one 6s and one 5d electrons to contribute the electronic shell closure. The sp-d hybridizations as well as the d-d interactions between the host Au and dopant Pt atoms result in the enhanced stabilities of AuPt clusters.

Density Functional Study of Molecular Hydrogen Adsorption on Small Gold–Copper Binary Clusters

“…To calibrate the accuracy of this approach, we first compared the calculated spectroscopic parameters of the smallest Au 2 and Cu 2 clusters with previous theoretical results and experimental data. While the calculated Au-Au bond length (2.55 Å ) agrees well with the other DFT studies [26][27][28], the previous CCSD(T) result (2.48 Å ) [29] and the experimentally observed value are somewhat smaller (2.47 Å ) [30]. [32]).…”

Effects of micro-water on decomposition of the environment-friendly insulating medium C5F10O

“…20 To evaluate the affection of micro-water on the insulation performance of C 5 F 10 O, the ionization parameters of the decomposition products were obtained, including the ionization energy (IE), electron affinity energy (EA), and energy bandwidth (Eg) between the highest occupied orbit and the lowest unoccupied orbit (HOMO-LUMO). 21 By comparing the ionization parameters, revealing the effect of the decomposition products on the insulation properties of the system at the molecular level becomes possible. We can understand the effect of micro-water on the decomposition of C 5 F 10 O more comprehensively combing with the toxicity analysis.…”

“…The frontier molecular orbital theory points out that, for intermolecular reactions, when the reactants are close to each other, the occupied orbit of one molecule first interacts with the lowest unoccupied orbital of another molecule, and then electrons move from HOMO to LUMO. 21,22 The distribution of HUMO wave function of C 5 F 10 O is shown in Figure 2. C=O and its adjacent C atoms are seen as the largest electron density distribution sites with high reactivity, which may fracture under high-energy electric field or local overheating faults and then undermine the insulation of the system.…”

Monoxides of small terbium clusters: A density functional theory investigation

“…In addition, the bonding preference of different atoms gives another efficient way to construct good candidates for the global minima or to reduce the configuration space. In our previous works, this method has been used to treat transition metal (TM) clusters [45][46][47][48][49][50][51] and lanthanide clusters, 18,20,28 for which the lowest energy structures we obtained were positively confirmed by the subsequent works using the unbiased global optimizations. 13,[52][53][54][55][56][57] Following above approaches, we consider all possible configurations for small sizes (n = 2-7), but construct a large number of initial configurations for large sizes (n = [8][9][10][11][12][13][14] primarily at the additive and substitutive patterns from the low-lying structures of Tb n±1 , e.g., three different binding modes are intensively examined for the adsorption of oxygen atom: atop, bridge, and hollow sites.…”