Ultrafast dynamics of self-trapped excitons in silica revealed by ab initio simulations

Ultrafast dynamics of self-trapped excitons in silica revealed by ab initio simulations | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Ultrafast dynamics of self-trapped excitons in silica revealed by ab initio simulations Jean-Philippe Colombier, Arshak Tsaturyan, Djafar Iabbaden, Elena Kachan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8467232/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Self-Trapped Excitons (STEs) govern the optical and electronic response of silica, yet their formation mechanisms remain unclear due to the interplay of electronic relaxation, lattice distortion, and defect generation. To investigate STE formation under ultrafast photoexcitation, we combine adiabatic and non-adiabatic time-dependent density functional theory calculations with surface-hopping dynamics. We show that when atomic movement is constrained, excited electrons relax primarily through internal conversion and intersystem crossing. In contrast, fully unconstrained structures undergo Si–O bond breaking that creates localized defect states within the bandgap. We identify a STE level at 2.74 eV with a relaxation rate consistent with experimentally observed photoluminescence. Non-adiabatic population dynamics reveals that relaxation proceeds predominantly along the S2 → S1 → GS pathway, with triplet channels contributing only under specific structural conditions. The relaxation time of 353 fs is consistent with the experimentally fitted electron trapping time. Moreover, we show that electron-phonon coupling plays a crucial role in STE formation. Physical sciences/Materials science/Theory and computation/Electronic structure Physical sciences/Materials science/Materials for optics/Ultrafast photonics silica ultrafast laser-matter interaction non-adiabatic molecular dynamics adiabatic TDDFT self-trapped exciton Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8467232","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":570272079,"identity":"dcf5676b-0d7c-4fbb-a4b4-775140a36796","order_by":0,"name":"Jean-Philippe 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