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1.
The geometries, stabilities, electronic, and magnetic properties of hydrogen adsorption on Ru
n
clusters have been systematically investigated by using density functional theory with generalized gradient approximation.
The result indicates the absorbed species does not lead to a rearrangement of the basic cluster. For n > 2, three different adsorption patterns are found for the Ru
n
H2 complexes: One H atom binds to the Ru top site, and another H binds to the bridge site for n = 3, 5, 6, 8; bridge site adsorption for n = 4; hollow site and top site adsorption for n = 7. The adsorption energies display oscillation and reach the peak at n = 2, 4, 7, implying their high chemical reactivity. The small electron transferred number between H atoms and Ru
n
clusters indicates that the interaction between H atoms and Ru
n
clusters is small. When H2 is absorbed on the Ru
n
clusters, the chemical activity of corresponding clusters is dramatically increased. The absorbed H2 can lead to an oscillatory behavior of the magnetic moments, and this behavior is rooted in the electronic structure of the
preceding cluster and the changes in the magnetic moment are indicative of the relative ordering of the majority and minority
LUMO’s. The second order difference indicates 5 is magic number in Ru
n
H2 and Ru
n
clusters. 相似文献
2.
Chang-Geng Luo Hua-Long Jiang Gen-Quan Li Shuai Zhang Cheng Lu 《Structural chemistry》2016,27(2):457-465
The structures, relative stabilities, and electronic properties of pure Si n and Cs-doped silicon clusters (n = 2–12) are systematically investigated using the density functional theory at the B3LYP level. The optimized structures indicated that the lowest-energy structures of CsSi n are similar to those of pure Si n clusters and prefer the 3-dimensional configuration for n = 3–12. The relative stabilities of CsSi n clusters are analyzed based on the averaged binding energy, fragmentation energy, second-order energy difference, and HOMO–LUMO energy gap. It is found that CsSi6 and CsSi9 are the magic clusters, and the doping of Cs atom reduces the chemical stabilities of Si n frame. The Mulliken population analysis pointed out that the charges in the corresponding CsSi n clusters always transfer from Cs atom to Si n host in the range of 0.80–0.91 electron. In addition, the partial density of states, infrared, and Raman spectra is discussed. 相似文献
3.
Structure, stability and electronic property of the gold-doped germanium clusters: AuGe
n
(n = 2–13)
The structure, stability and electronic property of the AuGe n (n = 2–13) clusters with different spin configurations are systematically investigated with density-functional theory approach at UB3LYP/LanL2DZ level. In examining the lowest energy structures, it is found that the growth behaviors for the small-sized AuGe n (n = 2–9) clusters and relatively large-sized AuGe n (n = 10–13) clusters are different. As the number of Ge atom increases, the Au atom would gradually move from convex to surface and to interior sites. For the most stable structures of AuGe n (n = 10–13) clusters, the Au atom would be completely surrounded by the Ge atoms to form Au-encapsulated Ge n cages. Natural population analysis shows that the charges always transfer from the Au atom to the Ge n framework except for the AuGe2 cluster. This indicates that the Au atom acts as electron donor even the 5d orbitals of the Au atom are not significantly involved in chemical bonding. The analyses of the average atomic binding energies as well as the dissociation energies and the second-order differences of total energy show that the AuGe n clusters with n = 5, 9 and 12 are more stable than their neighboring ones, in which the bicapped pentagonal prism AuGe12 in D 2d symmetry is most stable. The highest occupied molecular orbital–lowest unoccupied molecular orbital gaps are explored to be in the region of semiconductors and the more stable clusters have slightly smaller gaps. It could be expected that the stable clusters might be considered as the novel building blocks in practical applications, e.g., the cluster-assembled semiconductors or optoelectronic material. 相似文献
4.
Dong-Sheng Hao Jin-Rong Liu Wen-Guang Wu Ju-Cai Yang 《Theoretical chemistry accounts》2009,124(5-6):431-437
The neutral Si n K (n = 2–8) clusters and their anions have been systematically studied by means of the higher level of Gaussian-3 schemes. Equilibrium geometries and electron affinities have been calculated and are discussed for each considered size. For neutral Si n K clusters, the ground state structure is found to be “attaching structure”, in which the K atom is bound to Si n clusters. The most stable isomer for their anions, however, is found to be “substitutional structures”, which is derived from Si(n+1) by replacing the Si atom with a K. The dissociation energies of K atom from the lowest energy structures of Si n K have also been estimated to examine relative stabilities. 相似文献
5.
Wei Song Bin Wang Jin-long Wang Ling Fu Chun-ying Pu Xiu-mei Xu Yong-sheng Zhu Chao-zheng He Gen-quan Li 《Journal of Cluster Science》2017,28(5):2575-2588
Using the density functional theory calculations with the PBE exchange–correlation energy functional, we have studied the low-energy structures and electronic properties of Ni–Al alloy clusters for adsorbing or doping an aluminum atom to Nin (n = 13, 19, 23, 26, 29 and 55) clusters. The most stable structures of NinAl are viewed as adding an Al atom at the hollow triangle and rhombus site of the icosahedron (n = 13, 55) and double-icosahedron (n = 19, 23, 26 and 29) structures, respectively. For Nin?1Al, it can be seen that an Al atom gradually moves from surface (n = 13, 19, 23 and 26) to the interior site (n = 29, 55) in the most stable structures. The electronic properties of the Ni–Al alloy clusters including binding energies, magnetic properties, charge transfer and density of states have also been studied. 相似文献
6.
Molecular dynamics simulations on the I?–benzene–Ar n clusters have been carried out using an atom(ion)-bond model to describe the nonelectrostatic contribution to the total interaction. Results for I?–benzene–Ar and I?–benzene–Ar n (n = 3, 18 and 25) are presented and some predicted properties are compared with those of the alkali cation–benzene clusters solvated by Ar atoms. 相似文献
7.
Two metal–organic coordination polymers, {Co(bbbi)0.5(bm)(Hbtc)} n (1) and {Ag2(bbbi)2(ntp)(H2O)·4H2O} n (2), [bbbi = 1,1-(1,4-butanediyl)bis-1H-benzimidazole, bm = benzimidazole, H3btc = 1,2,4-trimellitic acid, and H2ntp = 2-nitroterephthalic acid], have been hydrothermally synthesized and characterized by physico-chemical and spectroscopic methods and single-crystal diffraction. 1 Features a 1D ladder-like chain and is further connected by O–H···O hydrogen bonding interactions to yield a 3D supramolecular architecture. 2 Possesses a 1D infinite zigzag chain connected by bbbi ligands in bis-monodentate mode, which is further extended into a 3D complicated supramolecular network by face-to-face π–π stacking interactions and O–H···O hydrogen bonds. Moreover, both compounds exhibit catalytic properties on degradation of methyl orange in Fenton-like process. 相似文献
8.
Jia Cao Qi Li Zhi Xiang Wang Lou Jun Gao Feng Fu Bo Fan Yao Wang 《Journal of Cluster Science》2016,27(3):993-1004
The geometric structures, relative stabilities, magnetic properties of Mo-doped gold clusters Au n Mo(n = 1–10) have been investigated at the PBE1PBE/def2TZVP level of theory. The results show that molybdenum doping has a significant effect on the geometric structures and electronic properties of Au n Mo(n = 1–10) clusters. For the lowest energy structures of Au n Mo(n = 1–10), the two dimensional to three dimensional transition occurs at cluster size n ≥ 8, and their relative stabilities exhibit odd–even oscillation with the change of Au atom number. It is found that charge in corresponding Au n Mo clusters transfers from Mo atom to Au n host in the size range n = 1–7, whereas the charge in opposition direction in the size range n = 8–10. In addition, the magnetic properties of Au n Mo clusters are enhanced after doping single Mo atom into the corresponding gold clusters. Our results are valuable for the design of magnetic material. 相似文献
9.
The structures and hydrogen storage capacities of (AlN)n (n = 3-5) clusters have been systematically investigated by using density functional theoretical calculations. At ωB97xD/6-311 + G(d, p) level, the planar structures of (AlN)n (n = 3-5) can adsorb 6-10 H2 molecules with average adsorption energies in the range 0.16 to 0.11 eV/H2, which meet the adsorption energy criteria of reversible hydrogen storage. The gravimetric density of H2 adsorbed on (AlN)n clusters can reach 8.96 wt%, which exceed the target set by Department of Energy. The hydrogen adsorption energies with Gibbs free energy correction indicate that the adsorption of 6 H2 in (AlN)3, 8 H2 in (AlN)4 and 10 H2 in (AlN)5 is energetically favorable below 96.48, 61.43, and 34.21 K, respectively. These results are expected to motivate further the applications of clusters to be efficient hydrogen storage materials. 相似文献
10.
Variable temperature SQUID magnetometry measurements were made on a sample of commercially available nickel bis-1,5-cyclooctadiene (Ni(COD)2) is reported. The material is shown to be a mixed phase magnetic system where the Ni(COD)2 behaves as a diamagnet containing a paramagnetic component at low temperatures which we believe consists of elemental Ni clusters arising from the decomposition of the material. The magnetic response of the Ni clusters can be described by the combination of two Langevin functions, which indicate cluster magnetic moments of 1.8 μ B and 15 μ B suggesting Ni n clusters with n = 2–3 and n = 14–19. However, we demonstrate that these clusters appear to show a spin transition to an S = 0 state at low temperatures, which may be a consequence of interactions between the clusters and the surrounding organic medium. Nevertheless, our results suggest that Ni(COD)2 is a novel material for the study of Ni clusters embedded in a diamagnetic background material. 相似文献
11.
Viktor Vargaljuk Sergiy Okovytyy Volodymyr Polonskyy Olga Kramska Anatoly Shchukin Jerzy Leszczynski 《Journal of Cluster Science》2017,28(5):2517-2528
The initial steps of copper electrocrystallization process from aqueous solutions have been studied at DFT level of theory. It has been shown that Cu(H2O) unit is the final product of Cu2+-ions electroreduction. From this particle clusters Cun·aq are formed and grow. Aggregation of copper atoms to the Cun·aq clusters consists of two steps. The first step includes condensation of Cu(H2O) units to hydrated clusters Cun(H2O)n (n = 2–6). At the second step bonding of Cu(H2O) particles is accompanied by dehydration of clusters yielding Cun(H2O)m structures (n > m). Cluster Cu7·aq has been singled out as key structure based on calculated values of energies and Cu–Cu bond distances of Cun·aq clusters. This cluster is of D5h symmetry which is typical for copper microcrystals formed from aqueous solutions in electrocrystallization processes on foreign surface. This key particle could be considered as a critical nucleus. Number of copper atoms therein matches average dimension of critical nucleus. 相似文献
12.
Sayoko Nagashima Shota Furukawa Satoshi Kamiguchi Ryu Kajio Hiroshi Nagashima Aritomo Yamaguchi Masayuki Shirai Hideki Kurokawa Teiji Chihara 《Journal of Cluster Science》2014,25(5):1203-1224
A series of molecular rhenium sulfide clusters [Re6S8(OH)6?n (H2O) n ](4?n)? (n = 0, 2, 4, 6) catalyze dehydrogenation of alcohols, and hydrogenation of ketones and olefins in a hydrogen stream at 350 °C. The catalytic activities of the dianionic and neutral clusters (n = 2, 4) are lower than those of tetraanionic and dicationic clusters (n = 0, 6) for all the reactions. When 1,4-butanediol is allowed to react over K4[Re6S8(OH)6], dehydrogenation proceeds to yield 2-hydroxytetrahydrofuran and successively γ-butyrolactone above 300 °C. Over [Re6S8(H2O)6]SO4 dehydration proceeds to yield tetrahydrofuran above 250 °C. The thermal activation mechanisms of these clusters were studied by powder X-ray diffraction analyses, Raman spectrometry, extended X-ray absorption fine structure spectrometry, thermogravimetry, and differential thermal analyses. The catalytically active site of K4[Re6S8(OH)6] is an uncoordinated metal site (Lewis acid site) developed by the loss of a water molecule from two hydroxo ligands. The active site of [Re6S8(H2O)6]SO4 is a Brønsted acid site; the anhydrous aqua cluster dication disproportionates to a hydroxo cluster monocation and a proton. Both of the octahedral cluster frameworks are retained up to 500 °C. 相似文献
13.
The stability, infrared spectra and electronic structures of (ZrO2)n (n=3–6) clusters have been investigated by using density‐functional theory (DFT) at B3LYP/6‐31G* level. The lowest‐energy structures have been recognized by considering a number of structural isomers for each cluster size. It is found that the lowest‐energy (ZrO2)5 cluster is the most stable among the (ZrO2)n (n=3–6) clusters. The vibration spectra of Zr? O stretching motion from terminal oxygen atom locate between 900 and 1000 cm?1, and the vibrational band of Zr? O? Zr? O four member ring is obtained at 600–700 cm?1, which are in good agreement with the experimental results. Mulliken populations and NBO charges of (ZrO2)n clusters indicate that the charge transfers occur between 4d orbital of Zr atoms and 2p orbital of O atoms. HOMO‐LUMO gaps illustrate that chemical stabilities of the lowest‐energy (ZrO2)n (n=3–6) clusters display an even‐odd alternating pattern with increasing cluster size. 相似文献
14.
Structural and Magnetic Properties of CoGen− (n=2–11) Clusters: Photoelectron Spectroscopy and Density Functional Calculations
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Xiao‐Jiao Deng Dr. Xiang‐Yu Kong Dr. Xi‐Ling Xu Dr. Hong‐Guang Xu Prof. Dr. Wei‐Jun Zheng 《Chemphyschem》2014,15(18):3987-3993
A series of cobalt‐doped germanium clusters, CoGen?/0 (n=2–11), are investigated by using anion photoelectron spectroscopy combined with density functional theory calculations. For both anionic and neutral CoGen (n=2–11) clusters, the critical size of the transition from exo‐ to endohedral structures is n=9. Natural population analysis shows that there is electron transfer from the Gen framework to the Co atom at n=7–11 for both anionic and neutral CoGen clusters. The magnetic moments of the anionic and neutral CoGen clusters decrease to the lowest values at n=10 and 11. The transfer of electrons from the Gen framework to the Co atom and the minimization of the magnetic moments are related to the evolution of CoGen structures from exo‐ to endohedral. 相似文献
15.
Three new Co(II) coordination polymers, [Co(L1)(bpdc)] n (1), [Co(L2)(ndc)(H2O)·2H2O] n (2) and [Co(L3)(ndc)(H2O)·H2O] n (3) (L1 = 1,2-bis(5,6-dimethylbenzimidazole)ethane, L2 = 1,3-bis(5,6-dimethylbenzimidazole)propane, L3 = 1,4-bis(5,6-dimethylbenzimidazole)butane, H2bpdc = 4,4′-biphenyldicarboxylic acid, H2ndc = 2,6-naphthalenedicarboxylic acid) have been synthesized under hydrothermal conditions and structurally characterized by X-ray crystallography. All three complexes feature (4,4) networks that extend into 3D supramolecular frameworks via hydrogen bonding interactions. The luminescence properties and catalytic activities of these complexes with respect to the degradation of methyl orange in a Fenton-like process have been investigated. 相似文献
16.
Ze-Ting Zhang Yan-Yan Wang Rui Yang Rui Liu Yong Zhao Guang-hua Cui 《Transition Metal Chemistry》2016,41(2):169-178
Three cobalt(II) coordination polymers {[Co(L1)(nda)(H2O)2]·2H2O} n (1), [Co(L2)(tbi)(H2O)] n (2) and [Co(L2)(bpdc)(H2O)] n (3) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)-2-propanol, L2 = 1,3-bis(benzimidazol-1-yl)-2-propanol, H2nda = 2,6-naphthalenedicarboxylic acid, H2tbi = 5-tert-butyl isophthalic acid and H2bpdc = 4,4′-biphenyldicarboxylic acid) were synthesized and characterized by physicochemical and spectroscopic methods. Complex 1 exhibits a 1D loop-like structure, which is further extended into a 3D 3,3,4T31 network through two O–H···O hydrogen bonding interactions. Complex 2 displays a 1D ladder-like chain, arranged into a 2D supramolecular network with 3,3,4L34 topology via classical O–H···O hydrogen bonding interactions, whereas complex 3 features a 2D 3,4L13 layer structure and further assembles into a 3D framework with a twofold interpenetrating sqc65 topology through O–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of these complexes for the degradation of Congo red in a Fenton-like process have been investigated. 相似文献
17.
The hybrid HF/DFT method B3LYP has been employed to investigate the geometrical and electronic structures of AuC n (n = 1–11) clusters. The properties such as geometrical parameters and electronic energies are determined for open-chain and cyclic species. Our results indicate that the open-chain structures with low spin states (doublet) are more stable than the cyclic ones for the small sizes clusters (n ≤ 9), as the cluster sizes increase (n = 10, 11), the cyclic species are more stable. The incremental binding energies show a smooth even–odd alternation phenomenon for open-chain species, n-even (n is the numbers of C atom in the clusters) species have the stronger stabilities relative to the adjacent odd-numbered ones. In addition, the most favorable dissociation channels are determined by calculating the fragmentation energies accompanying various possible pathways. The studied clusters incline to be dissociated to Au + C n and AuC n?3 + C3 fragments. 相似文献
18.
Pakiza Begum Debajyoti Bhattacharjee Bhupesh Kr. Mishra Ramesh C. Deka 《Theoretical chemistry accounts》2014,133(1):1-11
The density functional theory (DFT) calculations within the framework of generalized gradient approximation have been employed to systematically investigate the geometrical structures, stabilities, and electronic properties of Pd n Si q (n = 1–7 and q = 0, +1, ?1) clusters and compared them with the pure ${\text{Pd}}_{n + 1}^{q}$ (n = 1–7 and q = 0, +1, ?1) clusters for illustrating the effect of doping Si atom into palladium nanoclusters. The most stable configurations adopt a three-dimensional structure for both pure and Si-doped palladium clusters at n = 3–7. As a result of doping, the Pd n Si clusters adopt different geometries as compared to that of Pd n+1. A careful analysis of the binding energies per atom, fragmentation energies, second-order difference of energies, and HOMO–LUMO energy gaps as a function of cluster size shows that the clusters ${\text{Pd}}_{4}^{ + }$ , ${\text{Pd}}_{4}$ , ${\text{Pd}}_{8}^{ - }$ , ${\text{Pd}}_{5} {\text{Si}}^{0, + , - }$ , and ${\text{Pd}}_{7} {\text{Si}}^{0, + , - }$ possess relatively higher stability. There is enhancement in the stabilities of palladium frameworks due to doping with an impurity atom. In addition, the charge transfer has been analyzed to understand the effect of doped atom and compared further. 相似文献
19.
Using density functional theory (DFT) method with 6-31G* basis set, we have carried out the optimizing calculation of geometry, vibrational frequency and thermodynamical stability for (AlN) n + and (AlN) n + (n=1–15) clusters. Moreover, their ionic potential (IP) and electron affinity (EA) were discussed. The results show that the electrical charge condition of the cluster has a relatively great impact on the structure of the cluster and with the increase of n, this kind of impact is reduced gradually. There are no Al-Al and N-N bonds in the stable structure of (AlN) n + or (AlN) n -, and the Al-N bond is the sole bond type. The magic number regularity of (AlN) n + and (AlN) n - is consistent with that for (AlN) n , indicating that the structure with even n such as 2, 4, 6, ... is more stable. In addition, (AlN10 has the maximal ionization power (9.14 eV) and the minimal electron affinity energy (0.19 eV), which manifests that (AlN)10 is more stable than other clusters. 相似文献
20.
Yudai Ogata Yukio Kawashima Kaito Takahashi Masanori Tachikawa 《Theoretical chemistry accounts》2015,134(1):1-6
We carried out ab initio path integral molecular dynamics simulations at room temperature for OH?(H2O) n (n = 1, 2) clusters to elucidate the ionic hydrogen bond structure with full thermal and nuclear quantum effects. We found that the hydrogen-bonded proton is located near the water molecule in the case of n = 2, while the proton is located at the center between hydroxide ion and the water molecule in the case of n = 1. Thus, the solvated hydroxide structure \({\text{HO}}{-}{\text{H}} \cdots{\text{OH}}\) is found in n = 2, while the proton sharing hydroxide structure \({\text{HO}} \cdots {\text{H}} \cdots {\text{OH}}\) is in n = 1. We found that the nature of hydrogen bonds significantly changes with the number of water molecules around the hydroxide. We also compared these results with those of F?(H2O) n (n = 1, 2) clusters. 相似文献