Parallel implementation of density functional theory within the real space pseudopotential approach

This paper describes a parallel implementation of total energy density functional theory (DFT) within the real space pseudopotential approach. Our parallel implementation is based on a public domain serial real space pseudopotential code Octopus developed by M. A. L. Marques, A. Castro, G. F. Bertsch, and A. Rubio (2003). In the real space pseudopotential approach, the quantities of interest such as single-particle orbitals are expanded on a 3D uniform grid, the differential operators are computed using high-order finite-difference formulas, and the electron-ion interaction is described by first-principles pseudopotentials. The parallelism is achieved by partitioning the real space grid into subdomains, which are allocated to computer processors. The partitioning scheme employed in our implementation and the communications involved, along with tests of the scalability of the code are discussed.