Abstract:The global minimum structures of pure and boron doped silver clusters up to 16 atoms are determined through ab initio calculations and unbiased structure searching methods. The structural and electronic properties of neutral, anionic, and cationic Ag(n)B (n ≤ 15) and Ag(n)B2 (n ≤ 14) clusters are much distinct from those of the corresponding pure silver. Considering that Ag and B possess one and three valence electrons, respectively, both the single and the double boron-atom doped silver clusters with even num… Show more
The structural, electronic, and magnetic properties of AgnV (n = 1–12) clusters have been studied using density functional theory and CALYPSO structure searching method. Geometry optimizations manifest that a vanadium atom in low-energy AgnV clusters favors the most highly coordinated location. The substitution of one V atom for an Ag atom in Agn + 1 (n ≥ 5) cluster modifies the lowest energy structure of the host cluster. The infrared spectra, Raman spectra, and photoelectron spectra of AgnV (n = 1–12) clusters are simulated and can be used to determine the most stable structure in the future. The relative stability, dissociation channel, and chemical activity of the ground states are analyzed through atomic averaged binding energy, dissociation energy, and energy gap. It is found that V atom can improve the stability of the host cluster, Ag2 excepted. The most possible dissociation channels are AgnV = Ag + Agn − 1V for n = 1 and 4–12 and AgnV = Ag2 + Agn − 2V for n = 2 and 3. The energy gap of AgnV cluster with odd n is much smaller than that of Agn + 1 cluster. Analyses of magnetic property indicate that the total magnetic moment of AgnV cluster mostly comes from V atom and varies from 1 to 5 μ
B. The charge transfer between V and Ag atoms should be responsible for the change of magnetic moment.
The structural, electronic, and magnetic properties of AgnV (n = 1–12) clusters have been studied using density functional theory and CALYPSO structure searching method. Geometry optimizations manifest that a vanadium atom in low-energy AgnV clusters favors the most highly coordinated location. The substitution of one V atom for an Ag atom in Agn + 1 (n ≥ 5) cluster modifies the lowest energy structure of the host cluster. The infrared spectra, Raman spectra, and photoelectron spectra of AgnV (n = 1–12) clusters are simulated and can be used to determine the most stable structure in the future. The relative stability, dissociation channel, and chemical activity of the ground states are analyzed through atomic averaged binding energy, dissociation energy, and energy gap. It is found that V atom can improve the stability of the host cluster, Ag2 excepted. The most possible dissociation channels are AgnV = Ag + Agn − 1V for n = 1 and 4–12 and AgnV = Ag2 + Agn − 2V for n = 2 and 3. The energy gap of AgnV cluster with odd n is much smaller than that of Agn + 1 cluster. Analyses of magnetic property indicate that the total magnetic moment of AgnV cluster mostly comes from V atom and varies from 1 to 5 μ
B. The charge transfer between V and Ag atoms should be responsible for the change of magnetic moment.
“…We employed the CALYPSO (Crystal structure AnaLYsis by Particle Swarm Optimization) searching method 37 38 coupled with DFT calculations for geometry optimization. This combined CALYPSO/DFT computational approach has been previously used to search for low-lying sulphur clusters 39 , boron clusters 40 , and boron doped silver clusters 41 . Within the CALYPSO structure search, we adopted the global version of the particle swarm optimization (PSO) algorithm to finely explore the potential energy surface for each cluster size.…”
We performed an unbiased structure search for low-lying energetic minima of neutral and charged palladium PdnQ (n = 2–20, Q = 0, + 1 and –1) clusters using CALYPSO method in combination with density functional theory (DFT) calculations. The main candidates for the lowest energy neutral, cationic and anionic clusters are identified, and several new candidate structures for the cationic and anionic ground states are obtained. It is found that the ground state structures of small palladium clusters are more sensitive to the charge states. For the medium size Pdn0/+/– (n = 16–20) clusters, a fcc-like growth behavior is found. The structural transition from bilayer-like structures to cage-like structures is likely to occur at n = 14 for the neutral and cationic clusters. In contrast, for the anionic counterparts, the structural transition occurs at Pd13–. The photoelectron spectra (PES) of palladium clusters are simulated based on the time-dependent density functional theory (TD-DFT) method and compared with the experimental data. The good agreement between the experimental PES and simulated spectra provides us unequivocal structural information to fully solve the global minimum structures, allowing for new molecular insights into the chemical interactions in the Pd cages.
“…The energy difference between the HOMO (highest occupied molecular orbital) and the LUMO (lowest unoccupied molecular orbital) is known as molecular orbital energy gap ( E gap ). E gap can be used to measure the capability of an electron to transfer from an occupied orbital to an unoccupied orbital …”
The structural and electronic properties of ternary Al x Ti y Ni z clusters, where x, y, and z are integers and x + y + z = 6, are investigated. Both Slater, Vosko, Wilks, and Nusair and B3LYP exchange-correlation (XC) functionals are employed in a two-stage density functional theory (DFT) calculations to generate these clusters. In the first stage, a minimum energy cluster structure is generated by an unbiased global search algorithm coupled with a DFT code using a light XC functional and small basis sets. In the second stage, the obtained cluster structure is further optimized by another round of global minimization search coupled with a DFT calculator using a heavier XC functional and more costly basis set. Electronic properties of the structures are illustrated in the form of a ternary diagram. Our DFT calculations find that the thermodynamic stability of the clusters increases with the increment in the number of constituent nickel atoms. These results provide a new insight to the structure, stability, chemical order, and electronic properties for the ternary alloy nanoclusters.
K E Y W O R D SAl-Ti-Ni ternary alloy clusters, electronic structures, first-principles calculations, ground-state structures 1 | INTRODUCTION Atomic clusters are aggregates of atoms ranging from a few to thousands of atoms or molecules. Nanoclusters are atomic clusters with a diameter in the order of nanometers. They exhibit distinctly different electronic and structural behaviors compared with their larger size counterpart due to low dimensional and quantum confinement effects. [1] From the year 2000 onward, transition metal clusters had been intensively studied, both experimentally [2][3][4][5][6][7] and computationally. Nanoclusters, mainly binaries or ternaries, have attracted much attention due to their broad applications in catalysis, [32][33][34] magnetic-recording materials, [35] and biological applications, to name a few. For example, FeAlAu n (n = 1 − 6), [36] Fe-Co-Ni, [1,37,38] Fe-Co-Pd, [39] and Ag-Au-Pd [40] trimetallic clusters have been studied for their magnetic, electronic, and structural properties.In the search of the ground-state structures of ternary alloy clusters, one common practice is to generate them based on classical and semiclassical methods such as adoption of Gupta potential, Sutton-Chen potential, and others empirical potentials. These empirical or semiempirical results commonly show that the ground-state structures of the small clusters are in the shape of an icosahedron, whereas truncated octahedron and a truncated decahedral structure is favored by the large clusters. [2] Structural evolution of cluster can be explained and tackled by classical and semiclassical approaches, but these methods may fail if the electronic effects from valence electrons of the atoms have to be taken into account. [1,37,38] Using classical and semiclassical approaches in the search of ground-state configurations for transition metal clusters will produce unreliable results, due to the existence of localized d orbitals. ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
