Nonlocal energy optimized (NEO) kernel for the formation energies of alloys and surface energies of metals

Semi-local Density Functional Theory (DFT) includes the self-interaction error and misses the long-range van der Waals interaction. One possible remedy of these failures is the direct Random Phase Approximations (RPA). RPA stands on the highest rung of Jacob’s ladder of density functional approximations and includes the occupied and unoccupied Kohn Sham orbitals. However, the direct RPA is limited by neglecting the short ranged-correlation captured by an exchange-correlation kernel. Kernels based on the uniform electron gas model have shown some improvement over RPA and are computationally as affordable as RPA itself within PAW/pseudopotential codes. In this work, we are using the nonlocal energy-optimized (NEO) exchange-only kernel [1,2] to assess the formation energies of some intermetallic alloys and surface energies of some metals. These physical examples were chosen because they require a very delicate interplay of the short and long-range correlation in the kernel-corrected RPA and therefore a sophisticated way to construct the model kernel.

[1] J.E. Bates, S. Laricchia and A. Ruzsinszky, Phys. Rev. B 93, 045119 (2016)
[2] A. Ruzsinszky, L.A. Constantin, and J.M. Pitarke, Phys. Rev. B 94, 165155 (2016)