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arXiv · 1703.10738

Direct extraction of excitation energies from ensemble density-functional theory

Zeng-hui Yang·Aurora Pribram-Jones·Kieron Burke·Carsten A. Ullrich
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Abstract

A very specific ensemble of ground and excited states is shown to yield an exact formula for any excitation energy as a simple correction to the energy difference between orbitals of the Kohn-Sham ground state. This alternative scheme avoids either the need to calculate many unoccupied levels as in time-dependent density functional theory (TDDFT) or the need for many self-consistent ensemble calculations. The symmetry-eigenstate Hartree-exchange (SEHX) approximation yields results comparable to standard TDDFT for atoms. With this formalism, SEHX yields approximate double-excitations, which are missed by adiabatic TDDFT.

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Zeng-hui Yang, Aurora Pribram-Jones, Kieron Burke, Carsten A. Ullrich. 2017-06-29. Direct extraction of excitation energies from ensemble density-functional theory. https://doi.org/10.1103/physrevlett.119.033003

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