Real-space grid implementation of the projector augmented wave method

A grid-based real-space implementation of the Projector Augmented Wave (PAW) of P. E. Blochl Phys. Rev. B 50, 17953 (1994) for Density Functional (DFT) calculations is presented. The use of uniform 3D real-space grids representing wave functions, densities and potentials allows for flexible conditions, efficient multigrid algorithms for solving Poisson and-Sham equations, and efficient parallelization using simple real-space-decomposition. We use the PAW method to perform all-electron in the frozen core approximation, with smooth valence wave that can be represented on relatively coarse grids. We demonstrate accuracy of the method by calculating the atomization energies of twenty molecules, and the bulk modulus and lattice constants of bulk aluminum. show that the approach in terms of computational efficiency is comparable to plane-wave methods, but the memory requirements are higher.