Computationally Designed Crystal Structures of the Supertetrahedral GaC and GaSi Solids.

The structural, mechanical, electrical, and optical properties of new supertetrahedral structures -GaX (X = C, Si) were studied by using a solid state DFT calculation. The crystal structures of -GaX are built based on a diamond crystal lattice, in which pairs of adjacent carbon atoms are replaced by GaX fragments, where Ga is a tetrahedron of gallium atoms. Calculations have shown that new mixed-type supertetrahedral structures are dynamically stable, have densities of 3.

Molecular dynamics study of a new metastable allotropic crystalline form of gallium-supertetrahedral gallium.

A new metastable crystalline form of gallium has been computationally designed using density functional calculations with imposing periodic boundary conditions. The geometric and electronic structures of the predicted new allotrope were calculated on the basis of a diamond lattice in which all carbon atoms are replaced by gallium Ga tetrahedra. This form does not have any imaginary phonons, thus it is a metastable crystalline form of gallium.

Computationally Designed Crystal Structures of the Supertetrahedral AlX (X = B, C, Al, Si) Solids.

New metastable crystalline forms of the supertetrahedral AlX (X = B, C, Al, Si) solids have been computationally designed using density functional theory calculations with imposing of periodic boundary conditions. The geometric and electronic structures of the predicted new systems were calculated on the basis of the diamond lattice in which all carbon atoms are replaced by the AlX structural units, where X is boron, carbon, aluminum, and silicon atoms. The calculations showed that the dynamic stability of the AlX crystal structures critically depends on the nature of the bridging atom X: supertetrahedral AlC and AlSi solids are dynamically stable, whereas AlB and AlAl ones are unstable.

From Two- to Three-Dimensional Structures of a Supertetrahedral Boran Using Density Functional Calculations.

With help of the DFT calculations and imposing of periodic boundary conditions the geometrical and electronic structures were investigated of two- and three-dimensional boron systems designed on the basis of graphane and diamond lattices in which carbons were replaced with boron tetrahedrons. The consequent studies of two- and three-layer systems resulted in the construction of a three-dimensional supertetrahedral borane crystal structure. The two-dimensional supertetrahedral borane structures with less than seven layers are dynamically unstable.