Spurious interactions, and their correction, in the ensemble-Kohn-Sham scheme for excited States.
We observe that the direct Coulomb (Hartree) term appearing in the ensemble-density-functional theory for excited states contains an unphysical ("ghost") interaction which has to be corrected by the ensemble exchange and correlation functional. We propose a simple additive correction to the conventional ensemble exchange energy in the form of an orbital functional. By treating this corrected exchange energy functional self-consistently within the optimized effective potential method one finds a significant improvement of atomic excitation energies.
Gidopoulos
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Rutherford Appleton Laboratory, Isis Facility, Chilton, Didcot, Oxfordshire, OX11 0QX, United Kingdom.
Papaconstantinou
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Gross
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EK