Kohn-Sham potential for a strongly correlated finite system with fractional occupancy

Abstract

Using a simplified one-dimensional model of a diatomic molecule, the associated interacting density and corresponding Kohn-Sham potential have been obtained analytically for all fractional molecule occupancies $N$ between 0 and 2. For the homonuclear case, and in the dissociation limit, the exact Kohn-Sham potential builds a barrier at the midpoint between the two atoms, whose strength increases linearly with $N$, with $1<N\le 2$. In the heteronuclear case, the disociating KS potential besides the barrier also exhibits a plateau around the atom with the higher ionization potential, whose size (but not its strength) depends on $N$. An anomalous zero-order scaling of the Kohn-Sham potential with regards to the strength of the electron-electron repulsion is clearly displayed by our model; without this property both the unusual barrier and plateau features will be absent.

References in corpus (4)

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• Density functional with full exact exchange, balanced nonlocality of correlation, and constraint satisfaction
• Exchange and Correlation in Open Systems of Fluctuating Electron Number
• Kohn-Sham potentials in exact density-functional theory at non-integer electron numbers

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• Exact expressions for the height of the interatomic step in the exchange-correlation potential from the derivative discontinuity of the energy
• On the Geometric Potential and the Relationship between the Exact Electron Factorization and Density Functional Theory