Comparison between stability, electronic, and structural properties of cagelike and spherical nanodiamond clusters

Abstract

Ab initio density functional theory calculations were used to investigate cohesive, electronic, and structural properties of cagelike and spherical hydrogen terminated nanoparticles of diamond. Unlike cagelike nanodiamond particles, the variation of calculated energies of spherical ones is not monotonic. The variation range of the calculated energies and bond lengths of cagelike nanoparticles is much tighter than the variation range of spherical ones. In contrast to spherical nanodiamond particles, the C-C bond lengths of all cagelike nanoclusters are very similar to the bond length of bulk diamond. The comparison of stability, electronic highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps, and structural properties of these two classes of nanodiamonds shows that the effects of spatial symmetry, morphology, and C-H atom ratio are more important than the effect of nanoparticle sizes.

Strain-induced instability of spherical nanodiamond hydrocarbons: Effect of surfaceCHnand charging

“…From Ref. 12 we know that for the cagelike C particles, the formation energy increases and HOMO-LUMO energy gap decreases monotonically in agreement with monotonic variation in CH/ CH 2 +CH 3 ratio with the size. For the spherical C particles, the variation in formation energy and HOMO-LUMO energy gap with size reach a maximum and a minimum, respectively, 12 in agreement with nonmonotonic variation in CH/ CH 2 +CH 3 ratio with the size.…”

“…6, we have shown the variation in the CH/ CH 2 +CH 3 ratio with the nanoparticle size for cagelike and spherical nanodiamond particles and also in the inset of this figure we have shown the variation in the HOMO-LUMO energy gap of the cagelike and spherical particles with the size. 12 In Fig. 6, for the cagelike nanodiamond particles there is a monotonic increase in the ratio of CH/ CH 2 +CH 3 with size whereas the variation in this ratio for spherical particles is not monotonic and has a maximum value for C 35 H 36 .…”

“…We have already reported a strong correlation between the ratio of the bulk C atoms to the surface H atoms ͑C/H͒ with the formation energy and HOMO-LUMO energy gap. 12 Recently x-ray absorption spectroscopy ͑XAS͒ measurements have revealed an empirical correlation between electronic structure of the nanodiamond particles with the surface CH/CH 2 ratio. 13 In this paper, we explain the origin of the calculated structural instability and softness in specific sizes and geometries of spherical nanodiamond particles.…”

Study of the Quantum Confinement Effects and Stability Properties of Small Nanoclusters of Bare and Hydrogenated Diamond

“…In order to investigate the relative stability of bare and hydrogenated nanodiamond in this work, formation energy for each carbon atoms has been calculated according to the following equation [11,31]:…”

“…Raty et al [10] theoretically investigated the stability of bare and hydrogenated diamond with generalize gradient approximation (GGA) and they found that for particles between 2 and 3 nm, the hydrogenated diamond are less favored energetically in comparison to the bare diamond. Saani et al [11] used B3LYP exchange-correlation functional to investigate the stability and electronic properties of spherical and cage-like structure of hydrogenated nanodiamond. They showed that the spherical shapes of nanodiamond are more stable than the cage-like structures.…”