We use ab initio density functional calculations to determine the interaction of a graphene monolayer with the Si(111) surface. We found that graphene forms strong bonds to the bare substrate and accommodates the 12% lattice mismatch by forming a wavy structure consisting of free-standing conductive ridges that are connected by ribbon-shaped regions of graphene, which bond covalently to the substrate. We perform quantum transport calculations for different geometries to study changes in the transport properties of graphene introduced by the wavy structure and bonding to the Si substrate. Our results suggest that wavy graphene combines high mobility along the ridges with efficient carrier injection into Si in the contact regions.

We have reported the electronic structure, elastic, mechanical, phononic, and superconductivity properties for the orthorhombic WP single crystal, which has very recently been discovered to be the first superconductor among 5d-transition metal pnictides using density functional theory. The calculated electronic band structure and density of states reveal that WP is semimetallic in nature and the bands are mainly strengthened by the d-orbital of W atoms as well as determined several semi-Dirac-like points near the Fermi level. Elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and the brittle/ductile nature were determined. Some of these values were found to be compatible with other theoretical values that we found. The phonon spectrum shows that the orthorhombic MnP-type WP structure is dynamically stable. The calculated Debye temperature is comparable to the fitting experimental measurement of the normal state resistivity into the Bloch–Grüneisen function. The electron-phonon coupling parameter shows that WP is weakly coupled. We have also calculated the critical temperature (Tc) value of ∼0.81 K, which matches the experimental estimated value using electrical resistance, ac magnetic sensitivity, and specific temperature measurements.

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