Nonlocal Orbital-Free kinetic pressure tensors for the Fermi gas

A novel nonlocal density functional for the kinetic pressure tensor of a Fermi gas is derived. The functional is designed to reconcile the Quantum Hydrodynamic Model with the microscopic approaches, both for homogeneous equilibrium and dynamical regime. The derivation opens new ways to improve and implement further time-nonlocal functionals. The present proposal is systematically tested in and beyond the linear regime for the Fermi gas, as well as for some small sodium clusters, proving that it is quantitative superior to other existing functionals.