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As a potential "Superbug,"

Herein, using the first-principles methods based on the density functional theory, the electronic properties of HfSe$_2$/PtSe$_2$ van der Waals heterostructures (vdWHs) and the influence of stacking patterns, interlayer coupling effect, biaxial strain, and external electric field have been investigated systematically.We found that the stacking patterns could modulate the types of band alignment: AA, AB$'$ and AC$'$ belong to type-II band alignment, whereas AB, AC, AA$'$ belong to type-I band alignment.Among these six stacking patterns, the AA stacking pattern was the most stable, with an interlayer distance of 2.87 A and a bandgap of 1.0 eV, and the type-II band alignment was beneficial for separating electron and hole carriers.Our calculations showed that the electronic properties of HfSe$_2$/PtSe$_2$ vdWHs could be effectively modulated via vertical strain and biaxial strains:an interesting transition from type-II to type-I band alignment was observed in HfSe$_2$/PtSe$_2$ vdWHs upon applying vertical or biaxial strains.Moreover, the bandgap of the designed heterostructure could be effectively modified through the compressive strain and interlayer coupling.Our findings will provide a theoretical basis for the potential applications of HfSe$_2$/PtSe$_2$ vdWHs designing of multifunctional electronic and optoelectronic devices.

The effect of basis configuration on acoustic band structure in two-dimensional complex phononic crystals （PCs） was investigated. We found that when the basis configuration was changed, the irreducible Brillouin zone （BZ） of PCs might be changed too，and part of band extrema were no longer on the high-symmetry lines. In particular，the PCs with some basis configurations were forced to render the whole first BZ irreducible. Therefore，besides the high symmetrical PCs，only by throughout investigation of the BZ can we obtain the authentic band structures and band gaps for the lower symmetrical PCs with complex crystal lattice.