Non--adiabatic effects lead to the breakdown of the semi-classical phonon concept
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arXiv
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| Format: | Preprint |
| Published: |
2023
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| _version_ | 1866914881896185856 |
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| author | Marini, Andrea |
| author_facet | Marini, Andrea |
| contents | Phonon properties of realistic materials are routinely calculated within the Density Functional Perturbation Theory\,(DFPT). This is a semi--classical approach where the atoms are assumed to oscillate along classical trajectories immersed in the electronic Kohn--Sham density, treated quantistically. In this work I demonstrate that, in metals, non--adiabatic effects induce a gap between the DFTP phonon frequencies and the fully quantistic solution of the phonon Dyson equation. A gap that increases with the phonon energy width reflecting the breakdown of the semi--classical DFPT description. The final message is that non--adiabatic phonon effects can be included only by using a fully quantistic approach. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2303_09869 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Non--adiabatic effects lead to the breakdown of the semi-classical phonon concept Marini, Andrea Materials Science Mathematical Physics Phonon properties of realistic materials are routinely calculated within the Density Functional Perturbation Theory\,(DFPT). This is a semi--classical approach where the atoms are assumed to oscillate along classical trajectories immersed in the electronic Kohn--Sham density, treated quantistically. In this work I demonstrate that, in metals, non--adiabatic effects induce a gap between the DFTP phonon frequencies and the fully quantistic solution of the phonon Dyson equation. A gap that increases with the phonon energy width reflecting the breakdown of the semi--classical DFPT description. The final message is that non--adiabatic phonon effects can be included only by using a fully quantistic approach. |
| title | Non--adiabatic effects lead to the breakdown of the semi-classical phonon concept |
| topic | Materials Science Mathematical Physics |
| url | https://arxiv.org/abs/2303.09869 |