Nonlocal pseudopotential energy density functional for orbital-free density functional theory

Orbital-free density functional theory is an electronic structure method with a low computational cost enabling large-scale material simulations. Here the authors present a novel protocol which allows for the application of nonlocal pseudopotentials to orbital-free density functional theory. Orbital-free density functional theory (OF-DFT) is an electronic structure method with a low computational cost that scales linearly with the number of simulated atoms, making it suitable for large-scale material simulations. It is generally considered that OF-DFT strictly requires the use of local pseudopotentials, rather than orbital-dependent nonlocal pseudopotentials, for the calculation of electron-ion interaction energies, as no orbitals are available. This is unfortunate situation since the nonlocal pseudopotentials are known to give much better transferability and calculation accuracy than local ones. We report here the development of a theoretical scheme that allows the direct use of nonlocal pseudopotentials in OF-DFT. In this scheme, a nonlocal pseudopotential energy density functional is derived by the projection of nonlocal pseudopotential onto the non-interacting density matrix (instead of orbitals) that can be approximated explicitly as a functional of electron density. Our development defies the belief that nonlocal pseudopotentials are not applicable to OF-DFT, leading to the creation for an alternate theoretical framework of OF-DFT that works superior to the traditional approach.

Automated summary

The authors present a novel protocol that allows for the application of nonlocal pseudopotentials to orbital-free density functional theory (OF-DFT). They have developed a theoretical scheme that defies the traditional belief and enables the direct use of nonlocal pseudopotentials in OF-DFT.