Supplementary Information
Initial geometries, interaction mechanism and high stability of
silicene on Ag(111) surface
Junfeng Gao, Jijun Zhao*
Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian
University of Technology), Ministry of Education, Dalian 116024, China
Email: zhaojj@dlut.edu.cn (J. Zhao)
S0
S1. The C clusters configurations and formation energies in vacuum
Figure S1. Geometries and formation energies (eV per atom) of selected 2D carbon
clusters based on six-membered rings in vacuum. The original double-hexagon
configuration of C10 transforms into a ten-membered ring after relaxation.
S1
S2. Carbon clusters on Ag(111) surface
Figure S2. Geometries and formation energies (eV per carbon atom) of carbon
clusters on Ag(111) surface.(a) top view; (b) side view of four selected
CN@Ag(111)(N= 10, 13, 22, 24). Note that C10 configuration consisting of two
adjacent hexagons is preserved, different from the vacuum situation (see Fig. S1). C10
and C13 prefer upright standing on Ag(111) surface due to the strong orientation
preference of carbon edge bonds on metal surface. Larger carbon clusters (C22 and C24)
on metal surface form dome-like shape.
S2
S3. Triangle- and hexagon-based structures of Si10 and Si13 clusters on Ag(111)
Figure S3. Hexagon-based Si10-h (a) and Si13-h (d) silicene clusters on Ag(111)
surface after geometry optimization. The initial structures for triangle-based Si10-t (b),
Si13-t1 (e) and Si13-t2 (g) clusters on Ag(111) surface and the irregular structures (c, f,
h) after optimization, respectively. Their formation energies (eV per Si atom) are
labeled. Note that all triangle-based silicon clusters are less stable than corresponding
hexagon-based isomers. After geometry optimization, they transform into irregular
configurations by breaking the triangular lattices. In particular, a hexagonal ring is
formed spontaneously in Si13-t1 upon relaxation.
S3
S4. GS silicon clusters on Ag (111) surface
Figure S4. Geometries and formation energies (eV per silicon atom) of GS silicon
clusters on Ag(111) surface.
S4
S5. Local energy difference and diffusion barrier of Si atom on Ag (111) and
Rh(111) surface
Figure S5. Local energy difference and diffusion barrier (eV) of an individual
silicon atom on (a) Ag(111) surface and (b) Rh(111) surface.
S5
S6. Detailed buckling information of selected silicene clusters on Ag(111) surface
Figure S6. Detailed buckling information of selected silicene clusters on Ag(111)
surface.(a) Si10, (b) Si13, (c) Si22 , (d) Si24. For a clear view, the Ag(111) surface is
hided. The z coordinates (Å) of all three-coordinated silicon atoms are presented,
while the average z coordinate of Ag atoms in the top layer of Ag(111) slab is set as
zero for reference. The height differencesz of Si atoms are also provided for every
silicone clusters.
S6
S7. On-site charge of Si24 on Ag(111) surface
Figure S7. On-site Mulliken charges (|e|) of a hexagon-based Si24 cluster on Ag(111)
surface. The on-site charges range between 0.13 |e| and 0.08 |e| and are nearly
homogeneous. Hence, there is no dome-shape for Ag(111)-supported Si24 cluster and
the local tension in Si24 cluster induced by the Ag(111) surface is small. The slight
variation of on-site charges can be associated with small height difference due to low
buckling of silicene cluster (see Supplementary Fig. S6d online), that is, the lower
(higher) Si atoms carry more (less) on-site charges.
S7
S8. Structural information of silicene superstructures on Ag(111) surface
Table S8. Detailed structural information for various silicone superstructures on
three-layer slab of Ag(111) surface (corresponding to those in Fig.6 of main text):
periodicity, numbers of atoms, and lattice constants (LSi and LAg) of silicone and
Ag(111) supercells, mismatch Δ, range of Si-Si bond lengths (dSi-Si) and the average
length ( d ).The mismatch  is defined by Δ = (LSi – LAg)/LSi. The lattice constants of
silicene and Ag(111) surface unit cell are 3.89 Å and 2.89 Å, respectively.
Type
Silicene
LSi (Å)
(3 × 3),
I
14 atoms
d (Å)
11.560
0.86
2.319~2.381
2.351
10.011
+2.73
2.285~2.370
2.322
10.420
1.24
2.326~2.436
2.357
36 atoms
( 7  7)
( 13  13 ) ,
10.292
14 atoms
dSi-Si (Å)
(2 3  2 3 ) ,
10.292
III
Δ (%)
48 atoms
( 7  7)
II
LAg (Å)
(4 × 4),
11.661
18 atoms
S8
Ag(111)
39 atoms
S9. AIMD simulation of (5×5) silicene on (7×7) Ag(111) surface at 900 K
Figure S9. Snapshots from AIMD simulation of silicene on Ag(111) at 900 K. For
each graph, Ag atoms are not shown in top view. The important local disruptions are
labeled by red dash rings. Note that some defects are created in silicene ML at 0.8 ps
(b) and 1.4 ps (d), respectively; but they are spontaneously recovered very soon, i.e.,
in the next 0.1 ps (c). After heating at 900 K for 5 ps, the topological structure of
silicene lattice is preserved very well, confirming its high thermal stability on
Ag(111).
S9