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| Main Authors: | , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2503.17607 |
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| _version_ | 1866908277731753984 |
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| author | Griffin, Hadassah Kryjevski, Andrei |
| author_facet | Griffin, Hadassah Kryjevski, Andrei |
| contents | Boltzmann transport equation (BE) is a potent approach to dynamics of a photoexcited (nano)material. BE collision integrals for different relaxation channels can be systematically computed using the Kadanoff-Baym-Keldysh (KBK) formalism (also called NEGF) utilizing the Density Functional Theory (DFT) simulation output. However, accurate description of phonon-mediated relaxation in a general class of (nano)materials that includes exciton effects is still an outstanding problem. The approach proposed here is based on the observation that the non-adiabatic couplings of the DFT-based non-adiabatic molecular dynamics (NAMD) play the role of a time-dependent external potential coupled to the electrons. This allows application of the Keldysh approach resulting in the exciton-phonon BE collision integral, which incorporates exciton wave functions and energies obtained from Bethe-Salpeter equation. As an application, we augment BE with radiative recombination and photon-mediated exciton-exciton transition terms and then use it to calculate photoluminescence (PL) spectrum for several 1.5-$nm$ semiconductor chalcogenide nanocrystals, such as $Cd_{37}Pb_{31}Se_{68},~Cd_{31}Pb_{37}Se_{68},$ which are Janus-type, and for $Pb_{68}Se_{68}.$ |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_17607 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Phonon-mediated relaxation in nanomaterials from combining Density Functional Theory based non-adiabatic molecular dynamics with Kadanoff-Baym-Keldysh technique Griffin, Hadassah Kryjevski, Andrei Mesoscale and Nanoscale Physics Boltzmann transport equation (BE) is a potent approach to dynamics of a photoexcited (nano)material. BE collision integrals for different relaxation channels can be systematically computed using the Kadanoff-Baym-Keldysh (KBK) formalism (also called NEGF) utilizing the Density Functional Theory (DFT) simulation output. However, accurate description of phonon-mediated relaxation in a general class of (nano)materials that includes exciton effects is still an outstanding problem. The approach proposed here is based on the observation that the non-adiabatic couplings of the DFT-based non-adiabatic molecular dynamics (NAMD) play the role of a time-dependent external potential coupled to the electrons. This allows application of the Keldysh approach resulting in the exciton-phonon BE collision integral, which incorporates exciton wave functions and energies obtained from Bethe-Salpeter equation. As an application, we augment BE with radiative recombination and photon-mediated exciton-exciton transition terms and then use it to calculate photoluminescence (PL) spectrum for several 1.5-$nm$ semiconductor chalcogenide nanocrystals, such as $Cd_{37}Pb_{31}Se_{68},~Cd_{31}Pb_{37}Se_{68},$ which are Janus-type, and for $Pb_{68}Se_{68}.$ |
| title | Phonon-mediated relaxation in nanomaterials from combining Density Functional Theory based non-adiabatic molecular dynamics with Kadanoff-Baym-Keldysh technique |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2503.17607 |