Structure and magnetism of small rhodium clusters

Abstract

We report a systematic study of the structural and magnetic properties of free-standing rhodium clusters (Rh N , 4рNр26). The geometrical structures of the global minima and lowest energy isomers were obtained with a semiempirical Gupta potential and employing a global evolutive search algorithm. The spin-polarized electronic structure and related magnetic properties of these geometries were calculated by solving selfconsistently a spd tight-binding Hamiltonian. We determined the possible coexistence of different isomers and found that inclusion does not, in general, change significantly the magnetic moments obtained for the global minima structures. Results are compared with the experiment and with other theoretical calculations available in the literature.

Electronic structure and thermochemical properties of neutral and anionic rhodium clusters Rhn, n=2–13. Evolution of structures and stabilities of binary clusters RhmM (M=Fe, Co, Ni; m=1–6)

“…Unlike the results of Rh 2 , the rhodium trimer has two nearly degenerate states: a quartet equilateral triangle (D 3h ) 4 A 00 1 state and a sextet isosceles triangle (C 2v ) 6 A 2 state. This result agrees well with other calculations [14,43,44]. However, the newest studies on structure Rh n (n = 2-9) carried out by Beltrán and coworkers [11] indicated the isosceles triangle (C 2v , 6 A 2 ) is the global minimum of Rh 3 .…”

“…The higher symmetry D 5h of the Rh-5-B found in the quartet state is less stable than the ground state by 8.6 kcal/mol. These structures are in line with the recent calculations by Bae et al [15] and Anguilera-Granja et al [43]. Concerning Rh 5 , our DFT results also predict that it has two degenerate low-energy states, namely the nonet and septet states of Rh-5-A in favor of the high spin state.…”

“…The lowest-energy structure of Rh 4 has previously been reported [14,43,45] to be a tetrahedron. In subsequent study, Beltrán et al [11] revealed that the lowest-energy geometry of Rh 4 neutral could be a bent rhombus Rh-4-A with multiplicity 7.…”

Hybrid density functional study of small Rhn(n=2−15)clusters

“…11 In order to improve the atomistic understanding of those problems, a wide range of experimental and theoretical studies have been reported for rhodium clusters in the neutral, cationic, and anionic states. Most of the studies have addressed the atomic structure of Rh n as a function of size, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] the vibrational spectra, 24,25,28 magnetic moments, 3,10,12,14,16,18,22 polarizabilities, 16,29 and the catalytic activity for small molecules. 21,[30][31][32][33][34] Among those studies, hybrid-DFT calculations combined with experimental far-infrared multiple photon dissociation 24,25 have reported that Rh + n clusters have compact structures based on octahedron motifs for n = 6-12 (i.e., only compact structures can explain the vibrational spectra).…”

“…(iv) Atomic structures reported in the literature. 3,[12][13][14][15][16]18,[23][24][25][26]47 (v) A large number of different magnetic configurations were calculated for every atomic structure.…”