The Formation of Neutral Copper Clusters from Experimental Binding Energies and Reactivity Descriptors (original) (raw)
Related papers
Structural and energetic analysis of copper clusters: MD study of Cu n (n = 2-45)
Journal of the Brazilian Chemical Society, 2008
Simulações usando a dinâmica molecular foram efetuadas, considerando-se um potencial empírico para investigar geometrias, padrões de crescimentos, estabilidades de estruturas e energias para clusters de Cu n (n = 2-45). Os clusters estáveis otimizados foram calculados pelo rearranjo via processo de colisão. O presente procedimento apresenta-se como uma alternativa eficiente para a identificação do crescimento de clusters e como uma técnica de otimização. Foi verificado que os clusters de cobre preferem formar estruturas compactas tridimensionais em determinadas configurações enquanto os sistemas de tamanho médio apresentam simetria esférica. Além disso, também foram observadas correlações entre os arranjos atômicos e os números mágicos dos clusters. Particularmente, verificou-se que Cu 26 tem uma estabilidade equivalente ao sistema Cu 13. Molecular dynamics simulations, via an empirical potential, have been performed in order to investigate geometries, growing patterns, structural stabilities, energetics, and magic sizes of copper clusters, Cu n (n = 2-45). Possible optimal stable structures of the clusters have been generated through following rearrangement collision of the system in fusion regime. This process serves as an efficient alternative to the growing path identification and the optimization techniques. It has been found that copper clusters prefer to form three-dimensional compact structures in the determined configurations and the appearances of medium sizes are five fold symmetry on the spherical clusters. Moreover, relevant relations between atomic arrangements in the clusters and the magic sizes have been observed. Cu 26 may be accepted as another putative magic size like Cu 13 .
The Journal of Chemical Physics, 2002
In this paper we study nine neutral copper clusters through the theoretical characterization of their molecular structures, binding energy, electronic properties, and reactivity descriptors. Geometry optimization and vibrational analysis were performed using density functional theory calculations with a hybrid functional combined with effective core potentials. It is shown that reactivity descriptors combined with reactivity principles like the minimum polarizability and maximum hardness are operative for characterizing and rationalizing the electronic properties of copper clusters.
European Journal of Inorganic Chemistry, 1999
Density Functional Theory is used to study the influence of to the system, a simple expression is proposed to estimate its value from the eigenenergies of the frontier levels in neutral the size of copper clusters modeling the Cu(100) surface, on the electronic properties: ionization potential, electron and partially ionized systems. A detailed comparison of the geometric and electronic structures is made between the affinity, electronic chemical potential, and chemical hardness. The model clusters are chosen to have a bilayer model surface copper clusters, real copper clusters, and the actual metal surface; it is seen that the model surface clusters structure and range in size from 9 to 20 copper atoms. The chemical hardness being identified as the relaxation energy provide an easy extrapolation to the properties of the metal surface. of the frontier levels when an electron is removed or added a first approximation as monovalent (the 3d bonding and
Density Functional Theory Study of Copper Clusters
The Journal of Physical Chemistry B, 1999
A density functional theory study of copper clusters is presented. Fully optimized geometries, electronic structures, HOMO-LUMO gaps, spin density distributions, and ionization potentials are reported. The study is systematic starting with one-dimensional clusters followed by several planar structures and three-dimensional systems chosen to emulate (100) and (111) planes of bulk Cu. For the 1-D systems, it is found that the dissociation energy and ionization potential follow an oscillatory behavior that reflects a conjugate-like character indicative of a pair-occupation nature of copper. Calculated bond lengths, vibrational modes, ionization potentials, and dissociation energies for the smallest clusters agree very well with the available experimental information. A 1-D limit is rapidly reached by a chain system of 15 atoms. Most of the analyzed properties show substantial differences between the end atoms and those occupying central locations. The chain central atoms, with largest coordination numbers, bear the highest negative charge in the linear chains, and the same feature is observed in planar and 3-D structures. A semiempirical expression dependent on the cluster average coordination number is used to investigate the connection between the calculated cluster ionization potential and the local work function. The study confirms the validity of the cluster approach to improve the understanding of physicochemical properties at interfaces. * Corresponding authors. Fax: (803)-777-8265.
First principles studies on the growth of small Cu clusters and the dissociative chemisorption of H2
Physical Review B, 2006
The sequential growth of small copper clusters up to 15 atoms and the dissociative chemisorption of H 2 on the minimum energy clusters are studied systematically using density functional theory under the generalized gradient approximation. We found that small Cu n clusters grow by adopting a triangular growth pathway. The pentagon bipyramid structural arrangements are strongly favored energetically in the growth and the new addition in the cluster occurs preferably at a site where the atom is capable of interacting with more adjacent atoms. To understand the evolution of small copper clusters, we also performed calculations on selected icosahedral clusters ͑for n = 13, 19, 25, 55͒ and fcc-like clusters ͑n = 14, 23, 32, 41͒. By extrapolating/ interpolating the binding energies of triangular clusters, icosahedral clusters, and bulk-like clusters, we found that structural transitions from the triangular growth clusters to the icosahedral and fcc-like clusters occur at approximately n = 16 and n = 32, respectively. Subsequently, we performed extensive calculations on the dissociative chemisorption of H 2 on the minimum energy clusters. The chemisorption likely occurs near the most acute metal site with the two H atoms residing on the edges, which differs significantly from the chemisorption on Cu surfaces that usually takes place at the hollow sites.
Structure and stability of small copper clusters
Chemical Physics, 2002
The structure and stability of small copper clusters with up to ten atoms has been determined both for the neutral and the ionic clusters with density functional calculations. The calculations were of all-electron type. The structure optimization and frequency analysis were performed on the local density approximation level with the exchange correlation functional by Vosko, Wilk, and Nusair. Subsequently improved
Study of the Geometric Structure of Low-Atomic Copper Clusters Using Computer Simulation
2021
In this work, we investigated the geometric structure of small neutral copper clusters with low energy using the MD (Molecular Dynamics) method. When calculating the processes of interatomic interaction, we used a potential EAM (Embedded-atom method). A computer model of Cun (n = 2-13) clusters has been created. The geometric shapes of the Cu2, Cu3, Cu4, Cu5, Cu6, Cu7, Cu8, Cu9, Cu10, Cu11, Cu12, and Cu13 clusters have been studied and the structural parameters (Cu-Cu bond distance) have been calculated. The results obtained in the computer model were compared with the experimental results
Deposition of copper clusters on the Cu(111) surface
Surface Science, 2008
Results of a theoretical study of collision processes are reported. The relation between the impact energy for the deposition of copper clusters (with N = 13, 18, 38, and 55 atoms) on the Cu(1 1 1) surface and the structural and energetic stability of the products is investigated by means of molecular dynamics simulations. The interatomic interactions are described with a potential from the embedded atom method (EAM) family. The roles of the impact energy and cluster size are studied. It is shown that larger clusters change their structure less than smaller clusters, whereas the smaller (magic) Cu 13 and (non-magic) Cu 18 clusters lose rapidly their similarity to the original clusters for not too small impact energies. Moreover, for an impact energy of 0.5 eV/atom the structure of these clusters shows the lowest similarity to the original structures. In this case, the Cu 18 cluster forms a monolayer on the surface, with one atom of the surface substituted by an atom from the cluster, while the Cu 13 icosahedron forms a slightly deformed monolayer. Only at this impact energy monolayers can be formed. Instead, increasing the impact energy leads to a symmetrical pyramidal product for Cu 13 and to a double-layered cluster for Cu 18 . On the other hand, even at an impact energy of 0.9 eV/atom the final products of the larger fcc Cu 38 and the icosahedral Cu 55 clusters contain two, and three layers, respectively, on the surface.
Journal of the Brazilian Chemical Society, 2015
Basis sets of valence double and quadruple zeta qualities and the Douglas-Kroll-Hess (DKH) approximation are used to estimate the impact of an all-electron basis set and scalar relativistic effects on the structure, stability, and electronic properties of small neutral copper clusters (Cu n , n ≤ 8). At the Becke three-parameter for exchange and Perdew-Wang 91 for correlation (B3PW91) non-relativistic and relativistic levels of theory, the bond length, binding energy, ionization potential, electron affinity, chemical potential, chemical hardness, and electrophilicity index are calculated. The results show that the agreement with experiment improves significantly when the DKH Hamiltonian combined with an all-electron relativistic basis set is used. Polarizabilities and hyperpolarizability are also reported. At the B3PW91 level, all-electron basis sets are shown to be more reliable than effective core potential valence basis sets in the determination of the second hyperpolarizability of copper clusters.