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PRODID:-//Memento EPFL//
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SUMMARY:SpectroDynamics 2026: Connecting Computational Spectroscopic Metho
 ds Across the Electromagnetic Spectrum
DTSTART;VALUE=DATE:20260907
DTSTAMP:20260404T041505Z
UID:061dbf5da0ccc67e17a52ac9457792b9694aa371c97f07bc2cdea19e
CATEGORIES:Conferences - Seminars
DESCRIPTION:You can apply to participate and find all the relevant informa
 tion (speakers\, abstracts\, program\,...) on the event website: https://
 www.cecam.org/workshop-details/spectrodynamics-2026-connecting-computation
 al-spectroscopic-methods-across-the-electromagnetic-spectrum-1489.\n\nRegi
 stration is required to attend the full event\, take part in the social ac
 tivities and present a poster at the poster session (if any).  However\, 
 the EPFL community is welcome to attend specific lectures without reg
 istration if the topic is of interest to their research. Do not hesitate t
 o contact the CECAM Event Manager if you have any question.\n\nDescripti
 on\n\nLight provides one of the most detailed windows into molecules and m
 atter. Modern light sources allow the probing of equilibrium and non-equil
 ibrium phenomena with Å‐level spatial resolution and femto‐ to attose
 cond temporal precision. Advances in ultrafast laser technology\, together
  with the rise of X-ray free‐electron lasers and next-generation synchro
 tron sources\, have repeatedly pushed the boundaries of spectroscopic meth
 ods from low‐frequency collective modes in biomolecules to electronic an
 d core‐level dynamics. An extensive toolbox of linear and multidimension
 al spectroscopic techniques now spans the entire electromagnetic spectrum.
  Terahertz (THz) pulses can coherently drive intermolecular and lattice vi
 brations in solids and soft matter [1]\, Mid‐IR and Raman methods map vi
 brational energy (re)distribution in liquids and vibrational signatures of
  individual modes in complex molecules [2]. Visible spectroscopy tracks ul
 trafast charge dynamics in chromophores [3] and photochemical molecular pa
 thways [4]\, while X-ray sources from free-electron lasers and high-harmon
 ic generation setups enabled time-resolved X-ray diffraction of gas‐phas
 e [5] and condensed systems [6].\nDespite sharing common scientific goals\
 , the respective communities have traditionally operated in relative disco
 nnection from each other\, relying on different approximations\, targeting
  different observables\, and employing distinct numerical implementations.
  This disconnection manifests\, among other symptoms\, in the fact that sc
 hools\, conferences\, and workshops are often dedicated to a specific freq
 uency window (e.g. IR spectroscopy) or to simulation methods targeting a c
 lass of specific processes (e.g. vibrational dynamics). Opportunities for 
 dialogue and the building of a shared language are lacking. In fact\, whil
 e preparing this proposal\,  it became evident that even foundational ter
 ms like ab initio or quantum dynamics carry different meanings across comm
 unities.\nTo address this fragmentation\, the proposed CECAM school brings
  together researchers from diverse backgrounds to foster mutual understand
 ing and build lasting conceptual bridges. Over five days\, participants wi
 ll engage with both the theoretical foundations and practical implementati
 ons of spectroscopies across different communities. We will highlight the 
 fact that despite their apparent differences\, all spectroscopic methods c
 an be traced back to a common starting point: a light–matter Hamiltonian
  that includes the quantum description of electronic\, nuclear\, and photo
 nic degrees of freedom. From this unified framework\, we will explore how 
 different approximations—introduced at various stages—lead to the dist
 inct theoretical approaches adopted in each field.\nThe first part of the 
 school will focus on approaches that solve the exact quantum molecular dyn
 amics in reduced dimensionality. Within this framework\, molecules are tre
 ated fully quantum-mechanically\, while light is treated classically as an
  external perturbation within the dipole approximation. From the matter pe
 rspective\, this means that the full electron + nuclear wavefunction is ac
 cessible\, offering a great level of detail and information\, and the accu
 rate treatment of non-Born-Oppenheimer dynamics. From the light perspectiv
 e\, this means that spectroscopic signals are conveniently calculated via 
 the response function approach (RFA) [7]\, which is however only valid in 
 the weak field limit. Recently\, the RFA has been used to design and simul
 ate several spectroscopic signals of femtosecond molecular photochemistry 
 using novel X-ray pulse sources [8]\, including stimulated X-ray Raman [9]
 \, transient X-ray absorption and transmission [10]\, and many others [11]
 .\nIn the second part\, we will shift the focus to longer time scales with
  more degrees of freedom and study larger molecules in explicit environmen
 ts (solvent\, substrate\, etc). In these cases\, it is common practice to 
 apply the Born-Oppenheimer approximation and take the classical limit for 
 the nuclei\, while keeping the electrons quantum\, leading to (finite temp
 erature) molecular dynamics (MD) approaches. To make these simulations com
 putationally tractable\, while retaining an explicit description of the el
 ectrons\, electron–electron interactions are typically simplified using 
 ground-state density functional theory (DFT). This approach\, commonly ref
 erred to as ab initio molecular dynamics (AIMD)\, enables the simulation o
 f vibrational spectroscopies such as infrared (IR) and Raman [12\,13]\, as
  well as surface-specific techniques like sum-frequency generation (SFG) [
 14\,15]. To access larger system sizes and longer simulation timescales\, 
 forces can be derived from classical interatomic potentials\, facilitating
  the convergence of multidimensional spectroscopic observables such as THz
 -Raman spectra [16]. Alternatively\, forces can be learned directly from f
 irst-principles data using machine-learning (ML) models\, enabling ML-driv
 en molecular dynamics and spectroscopy [17-21].  Through path integral te
 chniques\, the quantum nature of the nuclei can be recovered\, which is pa
 rticularly important for systems containing light atoms\, such as hydrogen
  [22-24].\nThe third part of the school will explore what happens when the
  primary interest shifts from vibrational to electronic dynamics. In this 
 context\, the electron dynamics at the DFT level can be incorporated by co
 nsidering its time-dependent version (TDDFT)\, where the exchange-correlat
 ion functionals are usually adiabatic. With this method\, UV-visible absor
 ption [25]\, circular dichroism [26]\, inelastic X-ray scattering\, and el
 ectron energy loss [27]\, and other spectroscopies can be computed. Finall
 y\, there are situations in which strong light-matter coupling demands an 
 explicit treatment of the photons [28]. These can be reintroduced either b
 y dressing the Kohn-Sham Hamiltonian with electron-photon exchange-correla
 tion potentials (known as quantum-electrodynamics DFT\, or QEDFT) [29] or 
 by a semiclassical treatment of the photons solving Maxwell’s equations 
 (the Maxwell-TDDFT method)[30]. These methods enable the calculation of sp
 ectra in cavities or arbitrary electromagnetic environments [31]\, and can
  account for polaritonic phenomena\, radiative lifetimes\, superradiance\,
  and many more.\nThis school brings together leading experts from exact qu
 antum dynamics\, ab initio MD\, ML‐enabled simulations\, and Maxwell–T
 DDFT to forge a common language and cross‐fertilize ideas. Lectures will
  cover both the fundamental principles and the latest advances in each are
 a\, highlighting current applications and open challenges. Complementing t
 he lectures\, hands-on tutorials will reinforce foundational concepts and 
 provide important hands-on experience on several popular computational app
 roaches (see hands-on section below).\nBy spanning the electromagnetic spe
 ctrum and the hierarchy of theoretical methods\, this school will equip Ph
 D students and postdocs with a unified\, multi‐scale\, and inter-communi
 ty perspective on quantum dynamics and spectroscopy. Participants will lea
 ve with both a solid grounding in foundational techniques and direct exper
 ience of the latest computational frontiers\, ready to tackle open challen
 ges in molecular and materials science.\n\nReferences\n\n[1] P. Hamm\, The
  Journal of Chemical Physics\, 141\, (2014)\n[2] M. Svendsen\, K. Thygese
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LOCATION:BCH 2103 https://plan.epfl.ch/?room==BCH%202103
STATUS:CONFIRMED
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