Ab initio simulations of electronic spectra i liquids and dynamics in excited states


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Svensk sammanfattning

Hur bryts en kemisk binding? Vad händer i vanligt vatten på en
mikroskopisk nivå? Mycket av vår grundläggande förståelse av kemiska reaktioner
och växelverkan mellan molekyler baseras på teoretiska metoder. Men realismen i
dessa modeller måste ständigt frågasättas. Därför är kopplingen till experiment
avgörande för trovärdigheten av de teoretiska resultaten. De teoretiska
studierna sker i mycket nära samarbete med experimentella grupper, som
representerar spektroskopiska metoder som kan ge väldigt detaljerade
information on kemisk binding, molekylär struktur och reaktionsdynamik.

English summary

Ab initio molecular dynamics (MD) and spectrum simulations are
performed for the interpretation of x-ray, optical, electron and vibrational
spectroscopies with a focus on dynamical effects. Simulations relating to
recent and future experiments on ultra-fast processes with x-ray spectroscopy
give insight into processes studies with unprecedented time resolutions. A
continuous interplay between theory and experiment acts as a stimulus for the
method development.

English article

Molecular liquid and electrolytes are complex disordered systems
best treated with statistical mechanics. Ab initio molecular dynamics is used
to simulate aqueous solutions, alcohols and organic liquids. From the
simulations we can model x-ray emission spectra which contain information on
electronic structure and excited-state molecular dynamics and molecular interactions.

Simulations are performed to model static x-ray spectra and
time-resolved 2D-infra-red correlation spectroscopy on aqueous solutions, in
which the electronic information is essential. Time-resolved photo-emission
spectroscopy allows us to resolve the electronic changes during bond breaking
and ultra-fast reactions. Time-resolved soft x-ray spectroscopy is beginning to
produce results on the element-specific projection of the electronic structure,
and time-resolved hard x-ray spectra give direct access to the nuclear motion
in these processes. By studying the same system with different spectroscopic
techniques the theoretical simulations can act as a common denominator in the
combined theoretical and experimental effort.

Youtube entry

On the home-page of the experimental group at SLAC an small movie
is at display.


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Last updated on 2017-29-03 at 17:16