Adam Kirrander
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View article: Decoupling structural molecular dynamics from excited state lifetimes using few-femtosecond ultraviolet resonant dispersive waves
Decoupling structural molecular dynamics from excited state lifetimes using few-femtosecond ultraviolet resonant dispersive waves Open
Optical sources exploiting resonant dispersive wave (RDW) emission are set to revolutionize ultrafast science. We demonstrate this approach by investigating excited state dynamics in morpholine using time-resolved photoelectron imaging. Ex…
View article: Is there anybody out there? Ultrafast Rydberg–valence interactions in the photodissociation of trimethylamine
Is there anybody out there? Ultrafast Rydberg–valence interactions in the photodissociation of trimethylamine Open
Trimethylamine (TMA) is a tertiary aliphatic amine that stands as a potential marker for life beyond Earth due to only being naturally produced via biotic means. However, its propensity to undergo photodissociation in the gas phase when ex…
View article: Roadmap for Molecular Benchmarks in Nonadiabatic Dynamics
Roadmap for Molecular Benchmarks in Nonadiabatic Dynamics Open
Simulating the coupled electronic and nuclear response of a molecule to light excitation requires the application of nonadiabatic molecular dynamics. However, when faced with a specific photophysical or photochemical problem, selecting the…
View article: Triplets in the cradle: ultrafast dynamics in a cyclic disulfide
Triplets in the cradle: ultrafast dynamics in a cyclic disulfide Open
The effect of spin-orbit coupling on the "Newton's cradle"-type photodynamics in the cyclic disulfide 1,2-dithiane (C4H8S2) is investigated theoretically. We consider excitation by a 290 nm laser pulse and simulate the subsequent ultrafast…
View article: DONKEY: A Flexible and Accurate Algorithm for Clustering
DONKEY: A Flexible and Accurate Algorithm for Clustering Open
We propose an accurate clustering algorithm suitable for the varied and multidimensional data sets that correspond to temporal snapshots from on-the-fly nonadiabatic trajectory-based simulations of photoexcited dynamics. The algorit…
View article: Ultrafast ring-opening dynamics of 1,2-dithiane following ultraviolet absorption
Ultrafast ring-opening dynamics of 1,2-dithiane following ultraviolet absorption Open
View article: Photoexcited dynamics of the valence states of norbornadiene
Photoexcited dynamics of the valence states of norbornadiene Open
The non-radiative decay of photoexcited norbornadiene, which together with its isomer quadricyclane forms a molecular photoswitch, is investigated using surface-hopping non-adiabatic dynamics. The simulations are performed using four level…
View article: The Quantum Information Science Challenge for Chemistry
The Quantum Information Science Challenge for Chemistry Open
We discuss the goals and the need for quantum information science (QIS) in chemistry. It is important to identify concretely how QIS matters to chemistry, and we articulate some of the most pressing and interesting research questions at th…
View article: Revealing the reaction path of UVC bond rupture in cyclic disulfides with ultrafast x-ray scattering
Revealing the reaction path of UVC bond rupture in cyclic disulfides with ultrafast x-ray scattering Open
Disulfide bonds are ubiquitous molecular motifs that influence the tertiary structure and biological functions of many proteins. Yet, it is well known that the disulfide bond is photolabile when exposed to ultraviolet C (UVC) radiation. Th…
View article: Excited state dynamics of azanaphthalenes reveal opportunities for the rational design of photoactive molecules
Excited state dynamics of azanaphthalenes reveal opportunities for the rational design of photoactive molecules Open
View article: Electronic structure of norbornadiene and quadricyclane
Electronic structure of norbornadiene and quadricyclane Open
The ground and excited state electronic structure of the molecular photoswitches quadricyclane and norbornadiene is examined qualitatively and quantitatively.
View article: Ultrafast Ring-Opening Dynamics of 1,2-Dithiane Following Ultraviolet Absorption
Ultrafast Ring-Opening Dynamics of 1,2-Dithiane Following Ultraviolet Absorption Open
View article: Triplets in the cradle: ultrafast dynamics in a cyclic disulfide
Triplets in the cradle: ultrafast dynamics in a cyclic disulfide Open
The effect of spin–orbit coupling on the “Newton's cradle”-type photodynamics in the cyclic disulfide 1,2-dithiane (C 4 H 8 S 2 ) is investigated theoretically.
View article: Electronic structure of norbornadiene and quadricyclane
Electronic structure of norbornadiene and quadricyclane Open
The ground and excited state electronic structure of the molecular photoswitches quadricyclane and norbornadiene is examined qualitatively and quantitatively. A new custom basis set is introduced, optimised for efficient yet accurate calcu…
View article: XFEL SASE pulses can enhance time-dependent observables
XFEL SASE pulses can enhance time-dependent observables Open
X-ray free electron lasers (XFELs) have emerged as powerful sources of short and intense x-ray pulses. We propose a simple and robust procedure which takes advantage of the inherent stochasticity of self-amplified stimulated emission (SASE…
View article: Quantitative x-ray scattering of free molecules
Quantitative x-ray scattering of free molecules Open
Advances in x-ray free electron lasers have made ultrafast scattering a powerful method for investigating molecular reaction kinetics and dynamics. Accurate measurement of the ground-state, static scattering signals of the reacting molecul…
View article: NSF-UKRI Bilateral Workshop: Quantum Information Science in Chemistry
NSF-UKRI Bilateral Workshop: Quantum Information Science in Chemistry Open
This document summarizes the context and main outcomes of the discussions that took place during the NSF-UKRI bilateral workshop on Quantum Information Science in Chemistry, held on 12-13 February 2024, in Alexandria, Virginia (US). The wo…
View article: Ultrafast x-ray scattering and electronic coherence at avoided crossings: complete isotropic signals
Ultrafast x-ray scattering and electronic coherence at avoided crossings: complete isotropic signals Open
Nonadiabatic transitions at conical intersections and avoided crossings play a pivotal role in shaping the outcomes of photochemical reactions. Using the photodissociation of LiF as a model, this theoretical study explores the application …
View article: Using a multistate mapping approach to surface hopping to predict the ultrafast electron diffraction signal of gas-phase cyclobutanone
Using a multistate mapping approach to surface hopping to predict the ultrafast electron diffraction signal of gas-phase cyclobutanone Open
Using the recently developed multistate mapping approach to surface hopping (multistate MASH) method combined with SA(3)-CASSCF(12,12)/aug-cc-pVDZ electronic structure calculations, the gas-phase isotropic ultrafast electron diffraction (U…
View article: The Ring-Closing Reaction of Cyclopentadiene Probed with Ultrafast X-ray Scattering
The Ring-Closing Reaction of Cyclopentadiene Probed with Ultrafast X-ray Scattering Open
The dynamics of cyclopentadiene (CP) following optical excitation at 243 nm was investigated by time-resolved pump-probe X-ray scattering using 16.2 keV X-rays at the Linac Coherent Light Source (LCLS). We present the first ultrafast struc…
View article: Ultrafast electron diffraction of photoexcited gas-phase cyclobutanone predicted by <i>ab initio</i> multiple cloning simulations
Ultrafast electron diffraction of photoexcited gas-phase cyclobutanone predicted by <i>ab initio</i> multiple cloning simulations Open
We present the result of our calculations of ultrafast electron diffraction (UED) for cyclobutanone excited into the S2 electronic state, which is based on the non-adiabatic dynamics simulations with the Ab Initio Multiple Cloning (AIMC) m…
View article: Extracting the electronic structure signal from X-ray and electron scattering in the gas phase
Extracting the electronic structure signal from X-ray and electron scattering in the gas phase Open
X-ray and electron scattering from free gas-phase molecules is examined using the independent atom model (IAM) and ab initio electronic structure calculations. The IAM describes the effect of the molecular geometry on the scattering, but d…
View article: Ultrafast electron diffraction of photoexcited gas-phase cyclobutanone predicted by ab initio multiple cloning simulations
Ultrafast electron diffraction of photoexcited gas-phase cyclobutanone predicted by ab initio multiple cloning simulations Open
We present the result of our calculations of ultrafast electron diffraction (UED) for cyclobutanone excited into $S_2$ electronic state, which are based on the non-adiabatic dynamics simulations with \textit{Ab Initio} Multiple Cloning (AI…
View article: Valence shell electronically excited states of norbornadiene and quadricyclane
Valence shell electronically excited states of norbornadiene and quadricyclane Open
The absolute photoabsorption cross sections of norbornadiene (NBD) and quadricyclane (QC), two isomers with chemical formula C7H8 that are attracting much interest for solar energy storage applications, have been measured from threshold up…
View article: Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane Open
The light-induced ultrafast switching between molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Prior work observed signatures of ultrafast molecular dynamics in bot…
View article: Excited-state van der Waals potential energy surfaces for the NO A2Σ+ + CO2X1Σg+ collision complex
Excited-state van der Waals potential energy surfaces for the NO A2Σ+ + CO2X1Σg+ collision complex Open
Excited state van der Waals (vdW) potential energy surfaces (PESs) of the NO A2Σ+ + CO2X1Σg+ system are thoroughly investigated using coupled cluster theory and complete active space perturbation theory to second order (CASPT2). First, it …
View article: Automatic Clustering of Excited-State Trajectories: Application to Photoexcited Dynamics
Automatic Clustering of Excited-State Trajectories: Application to Photoexcited Dynamics Open
We introduce automatic clustering as a computationally efficient tool for classifying and interpreting trajectories from simulations of photo-excited dynamics. Trajectories are treated as time-series data, with the features for clustering …
View article: The contribution of Compton ionization to ultrafast x-ray scattering
The contribution of Compton ionization to ultrafast x-ray scattering Open
We investigate the role of Compton ionization in ultrafast non-resonant x-ray scattering using a molecular model system, which includes the ionization continuum via an orthonormalized plane wave ansatz. Elastic and inelastic components of …
View article: Robust Inversion of Time-Resolved Data via Forward-Optimization in a Trajectory Basis
Robust Inversion of Time-Resolved Data via Forward-Optimization in a Trajectory Basis Open
An inversion method for time-resolved data from ultrafast experiments is introduced, based on forward-optimization in a trajectory basis. The method is applied to experimental data from X-ray scattering of the photochemical ring-opening re…
View article: Mapping the photochemistry of cyclopentadiene: from theory to ultrafast X-ray scattering
Mapping the photochemistry of cyclopentadiene: from theory to ultrafast X-ray scattering Open
The photochemistry of cyclopentadiene is investigated using nonadiabatic dynamics simulations. Observables for ultrafast X-ray scattering experiments are predicted and mapped onto the structural dynamics.