Structure effects on the energetic, electronic, and magnetic properties of palladium nanoparticles

Abstract

A systematic investigation of palladium nanoparticles of up to 55 atoms (1.4 nm) has been conducted using density functional theory with a plane wave basis set. The stability of these nanoparticles increases with cluster size and dimensionality. It also depends strongly on the cluster structures through two factors, the coordination numbers of atoms and the strength of the single bonds. Both the energy gap between the highest occupied and the lowest unoccupied molecular orbitals and the magnetic moment change oscillatorily with cluster size. Furthermore, highly magnetic clusters tend to have large energy gaps. Analysis of the atom-resolved magnetic moment reveals that the local magnetism of a cluster depends mainly on the atomic bonding environments. A simple approach is proposed to predict relative stabilities of various structures for larger clusters. In addition, a structure factor is defined to correlate quantitatively various properties of the Pd clusters with their structures.

Theoretical study of linear monoatomic nanowires, dimer and bulk of Cu, Ag, Au, Ni, Pd and Pt

“…The obtained results on equilibrium lattice parameters, binding energies, break distances and forces are summarized in Table 1. It is worth noting that our calculated GGA bond length for the Pd dimer is in good agreement with the results of other DFT calculations [28][29][30] but somewhat lower than that from hybrid DFT calculations of Ref. [43] (2.53 Å for the triplet state).…”

“…This behavior is in sharp contrast with the properties of atomic and bulk Pd, which are known to be non-magnetic. The magnetism of Pd dimers has also been obtained in earlier calculations [28][29][30], [43] and [48]. The hybridization of atomic s and d states leading to appearance of an open-shell-like behavior is responsible for the magnetism of Pd dimers.…”

“…The binding energy of the Pd dimers calculated within GGA perfectly matches the results of Refs. [28][29][30]: 0.611 eV [28], 0.63 eV [29], and 0.646 eV [30]. Both GGA-PW91 and GGA-PBE predict larger lattice parameters and break forces but smaller binding energies compared to those obtained using LDA.…”

“…Recently the density functional calculations employing the self-interaction corrected (SIC) LDA-functional have shown that the values of the magnetic moments for Pd wire are 0.45 μB and 0.69 μB at equilibrium and break separations, respectively [25]. It is interesting to compare these results with magnetic moment of the Pd dimer which from ab initio pseudopotential calculations was found to be 1 μB per Pd atom [28][29][30]. The same result was obtained using a semi-empirical tight-binding method and SIESTA code based on the linear combination of pseudoatomic orbitals [31].…”

“…Magnetic properties of metal chains have also attracted considerable attention [19], [23][24][25][26][27][28][29][30][31][32]. In particular, it has been suggested that a magnetic ordering in Pd chains determines the conduction properties of the system [26].…”