Optimized Energy-Electronegativity Connection

Back from Paris, in the winter of 1964, Kohn met at the San Diego University of California his new post-doc Lu J. Sham with who propose to extract from HKl 2 theorems the equation of total energy of the ground 

Quantum Nanochemistry-Volume I Quantum Theory and Observability 

In fact, they propose themselves to find the correspondent of the stationary eigen-equation of Schrodinger type, employing the relationship between the electronic density and the wave function. 

Their basic idea consists in assuming a so-called orbital basic set for the iV-electronic system by replacing the integration in the relation (4.380) with summation over the virtual uni-electronic orbitals (p, i-, N, in accordance with Pauli principle, assuring therefore the HKl frame with maximal spin/orbital occupancy (Janak, 1978)  

the trial total eigen-energy may be rewritten as density functional of Eq. (4.381) nature expanded in the original form (Moscardo San-Fabian, 1991 Neal, 1998)  

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