Showing papers by "Paolo Giannozzi published in 2019"

Fast hybrid density-functional computations using plane-wave basis sets

Abstract: A new, very fast, implementation of the exact (Fock) exchange operator for electronic structure calculations within the plane-wave pseudopotential method is described in detail for both molecular and periodic systems, and carefully validated. Our method combines the recently proposed Adaptively Compressed Exchange approach, to reduce the number of times the exchange is evaluated in the self-consistent loop, with an orbital localization procedure that reduces the number of exchange integrals to be computed at each evaluation and potentially the compute time of each of them. The new implementation, already available in the Quantum ESPRESSO distribution, results in a speedup that is never smaller than 3-4x and that increases with the size of the system, according to various realistic benchmark calculations.

DFT study of graphene doping due to metal contacts

Abstract: The experimental results of Metal-graphene (M-G) contact resistance R C have been investigated in-depth by means of Density Functional Theory (DFT). The simulations allowed us to build a consistent picture explaining the R C dependence on the metal contact materials employed in this work and on the applied back-gate voltage. In this respect, the M-G distance is paramount in determining the R C behavior.