Nonlocal kinetic energy density functional via line integrals and its application to orbital-free density functional theory

Orbital-free density functional theory (OF-DFT) holds great promise for large-scale simulations since there is a linear scaling for the computational cost. However, OF-DFT faces an essential challenge on construction of accurate kinetic energy density functional (KEDF) for evaluating the noninteracting kinetic energy. In contrast to most of previous KEDFs constructed by satisfaction of known constraint conditions with pregiven forms, a nonlocal KEDF named Xu-Wang-Ma (XWM) is constructed from "scratch" by the line integrals, allowing us to ensure the inclusion of the corrected response behavior deviation from the uniform electron gas. XWM has been benchmarked on a range of model systems with different chemical environments. Numerical tests show that, in general, XWM can quantitatively reproduce the Kohn-Sham predictions of the basic bulk properties, electron density and vacancy formation energies. Particularly, the XWM functional is found to be numerically stable for random structures of both simple metals and several phases of silicon. The high accuracy and numerical stability of XWM functional yield improvements over most of KEDFs currently in use for applications, providing more insight into the development of new KEDFs.