  The geometric, electronic and magnetic properties of silicene-related systems
present the diversified phenomena through the first-principles calculations.
The critical factors, the group-IV monoelements, buckled/planar structures,
stacking configurations, layer numbers, and van der Waals interactions of
bilayer composites are taken into account simultaneously. The developed
theoretical framework is responsible for the concise physical and chemical
pictures. The delicate evaluations and analyses are conducted on the optimal
lattices, the atom- $\&$ spin-dominated energy bands, the atom-, orbital- $\&$
spin-projected vanHove singularities, and the magnetic moments. Most
importantly, they achieve the decisive mechanisms, the buckled/planar honeycomb
lattices, the multi-/single-orbital hybridizations, and the
significant/negligible spin-orbital couplings. Furthermore, we investigate the
stacking-configuration-induced dramatic transformations of the essential
properties by the relative shift in bilayer graphene and silicene. The lattice
constant, interlayer distance, the buckle height, and the total energy
essentially depend on the magnitude and direction of the relative shift: AA
$\rightarrow$ AB $\rightarrow$ AA$^{\prime}$ $\rightarrow$ AA. Apparently,
sliding bilayer systems are quite different between silicene and graphene in
terms of electronic properties, strongly depending on the buckled/planar
honeycomb lattices, the multi-/single-orbital hybridizations, the
dominant/observable interlayer hopping integrals, and the
significant/negligible spin interactions. The predicted results can account for
the up-to-date experimental measurements.
