Towards an orbital-free kinetic energy density functional for molecular systems*

A new kinetic energy density functional (KEDF) for systems composed of many atoms (molecular systems) is proposed. This KEDF contains the full von-Weizsacker KEDF as well as correction terms ("Pauli KEDF") appropriate for describing fermionic systems. Two of these correction terms are investigated: one from approximations based on the kinetic energy of fermions in an infinite well potential and the other from suitable averages of the kinetic energies of atoms. The peformance of these new KEDFs will be presented as well as possible routes for further development.