Surface energies and nanocrystal stability in the orthorhombic and π-phases of tin and germanium monochalcogenides

Abstract

Structures and energies of preferred surfaces of Sn and Ge monochalcogenides characterized and modelled.

Materials Modelling of π‐Phase Monochalcogenides

“…Experiments show that the (100) and (111) surfaces appear in the cubic and tetrahedral nanoparticles respectively. [40] The surface energies of the two most common surfaces of the π-phase in the monochalcogenides were calculated. The results are presented in Table 4.…”

“…Reproduced from ref. [40] with permission of The Royal Society of Chemistry. To obtain better insight into the bonding in the π-phase and the change in the bonding in the vicinity of the surface we calculated the density-of-states and the integrated local density-of-states of bulk π-SnS and π-SnS in the presence of the (100) surface ( Figure 11).…”

“…The DOS can be divided into four energy ranges, where ranges II and III are bonding and range IV is antibonding similar to other phases of the IV-VI monochalcogenides. [40] Range IV includes the lone pair which can be seen in the ILDOS iso-surface as a surface directed in the opposite direction of the chemical bond (Figure 11(c)). The bonding is a continuous spatial distribution of the ILDOS as shown in Figure 11(b) for range III To further study the bonding near the (100) surface we calculated the ILDOS in the vicinity of a 4 bonded S atom and a 4 bonded Sn atom formed due to bond breaking on the surface (Figure 12).…”

“…(top) Band structure calculation of π-SnS surface in the (100) facet 128 atoms supercell blow-up, electronic band gap 1.132 eV (direct). Reproduced from ref [40]. with permission of The Royal Society of Chemistry.…”

“…(b) is an ILDOS iso-surface of region III, (c) is an ILDOS iso-surface of region IV. Adapted from ref [40]. with permission of The Royal Society of Chemistry.…”