Ensemble density functional theory of ground and excited energy levels
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arXiv
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| Format: | Preprint |
| Published: |
2024
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| _version_ | 1866913655269883904 |
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| author | Fromager, Emmanuel |
| author_facet | Fromager, Emmanuel |
| contents | A Kohn-Sham density-functional energy expression is derived for any (ground or excited) state within a given many-electron ensemble along with the stationarity condition it fulfills with respect to the ensemble density, thus giving access to both physical energy levels and individual-state densities, in principle exactly. We also provide working equations for the evaluation of the latter from the true static ensemble density-density linear response function. Unlike in Gould's recent ensemble potential functional approach to excited states [arXiv:2404.12593], we use the ensemble density as sole basic variable. While a state-specific KS potential naturally emerges from the present formalism, at the exact ensemble Hartree-exchange-only (Hx) level of approximation, the standard implementation of orbital-optimized DFT for excited states is recovered when recycling the regular ground-state Hx-correlation functional in this context. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_17000 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Ensemble density functional theory of ground and excited energy levels Fromager, Emmanuel Chemical Physics Strongly Correlated Electrons A Kohn-Sham density-functional energy expression is derived for any (ground or excited) state within a given many-electron ensemble along with the stationarity condition it fulfills with respect to the ensemble density, thus giving access to both physical energy levels and individual-state densities, in principle exactly. We also provide working equations for the evaluation of the latter from the true static ensemble density-density linear response function. Unlike in Gould's recent ensemble potential functional approach to excited states [arXiv:2404.12593], we use the ensemble density as sole basic variable. While a state-specific KS potential naturally emerges from the present formalism, at the exact ensemble Hartree-exchange-only (Hx) level of approximation, the standard implementation of orbital-optimized DFT for excited states is recovered when recycling the regular ground-state Hx-correlation functional in this context. |
| title | Ensemble density functional theory of ground and excited energy levels |
| topic | Chemical Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2409.17000 |