Weizsacker Plus Thomas-Fermi Functionals

4 Corrected Weizsacker-Based Functionals 1.3.4.1 Weizsacker Plus Thomas-Fermi Functionals 

The simplest approach to correcting the Weizsacker functional is to add a fraction of Thomas-Fermi functional, forming a W + XTF functional. 

The only choice for X that is consistent with the uniform electron gas limit is A, = 1 unfortunately, that functional gives answers far above the true kinetic energy. 

This model can be improved by making the mixing factor X system dependent. Several authors considered making X dependent on M 2,149 These functionals give reasonable results for atomic kinetic energies, but, unfortunately, they are not size consistent. Moreover, when they are used in variational optimization, atomic densities have no shell structure. Thus, 

Shell structure is retained if one chooses X, so that it varies at different points in 

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