The plan is that Fridays, a speaker will give a presentation about his/her research. 

This is the time format we have: 

20 min + 10 min discussion for internal speakers

30 min + 10 min discussion for external speakers

Place: Local IKJ meeting room D3-104  (room Stølevik) + Microsoft Teams/Zoom (if possibe) 

 

Schedule for 2024:

 

01.11.2024, 15h30

Speaker: Konrad Wilke (TU Eindhoven, The Netherlands) 

Title: TBA

Abstract: TBA

 

27.09.2024, 15h15

Speaker: Prof. Idelfonso Nogueira 

Title: Data Science and Machine Learning in Natural Science

Abstract: TBA

 

03.07.2024, 15h15

Speaker: Angelos Xomalis 

Title: TBA

Abstract: 

Control over nanoscale constructs allows to assemble nanometre scale optical cavities.
Here I will discuss on how to design such cavities to reach extreme light localization in sub-nm mode volumes for optical interrogation of single molecules. Using advanced visible and infrared nanoscale spectroscopies, we are able to squeeze light wavelengths ranging from visible to mid-infrared regime within plasmonic nanogaps. These have encouraging prospective applications in molecular sensing as well as fundamental science.
Further, I will discuss current possibilities for optical studies at the Nanoscale Spectroscopies Group at IES-NTNU.

 

03.07.2024, 14h15

Speaker: Girish Lakhwani, ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Sydney, Australia 

Title: Organic optoelectronics in strong light-matter coupling regime 

Abstract:

Light can strongly couple with molecules to form polaritons that can enormously modify excited energy  states.  This  opens  new  approaches  to  engineering  new  light-based  technologies, promoting energy transfer over long distances, and making and breaking chemical bonds. [1]

In my talk, I will discuss our recent work focused on investigating the impact of strong light-matter coupling on the physics of organic semiconductors and devices. In the first case, I’ll address the potential of strong light-matter coupling to reduce excimer emission. Thermally activated delayed fluorescence (TADF) has attracted great attention due to its ability to harvest triplet excitons back into bright singlet excitons via reverse intersystem 
crossing (RISC) using thermal energy. However, in OLEDs, TADF emitters often suffer from molecular  aggregation,  which  limits  their  applicability  due  to  aggregation-induced  excimer formation that leads to a larger Stokes shift and broader emission spectrum. We show that under the strong light-matter coupling regime, both prompt and delayed excimer emission can be significantly suppressed and an increase in RISC rate constants up to 33% can be achieved providing a pathway to harvest non-radiative triplets more efficiently. [2] 
 
In the second case, I’ll will discuss the longer effective charge carrier lifetimes observed in OSCs  operating  under  strong  light-matter  coupling  that  we  reveal  is  a  result  of  reduced bimolecular recombination. [3] This study underscores the significant impact of strong light-matter coupling on modifying the device physics in OSCs, paving the way for engineering more efficient OSCs. 
 
References: 
[1] Tibben et al, Chem Rev 123, 8044 (2023) 
[2] Cho et al J Mater Chem C 11, 14448 (2023) 
[3] Tang et al ACS Photonics, 11, 1627 (2024) 

 

21.06.2024, 14h15

Speaker: Eirik Fadum Kjønstad

Title: Eight years of coupled cluster theory for excited state dynamics

 

30.05.2024, 9h00-9h45

Speaker: Prof. Peter Bolhuis, University of Amsterdam, The Netherlands

Title: Learning reaction coordinates and finding optimal model parameters from sampled trajectory ensembles

Room: D3-104 (rom Stolevik)

Abstract:

The reaction coordinate (RC) is the principal collective variable or feature that determines the progress along an activated or reactive process. A good RC is crucial for generating sufficient statistics with enhanced sampling. Moreover, the RC provides invaluable atomistic insight in the process under study. The optimal RC is the committor, which can be computed with brute force MD, or more efficiently by e.g. Transition Path Sampling. Novel schemes for transition path sampling using reinforcement learning can now effectively map the committor function. The interpretability of the committor, being a high dimensional function, remains very low. Applying dimensionality reduction can reveal the RC in terms of low-dimensional human understandable molecular collective variables (CVs) or order parameters. In the first part, I discuss several methods to perform this dimensionality reduction, such as likelihood maximization or symbolic regression, but they usually require a preselection of these low-dimension CVs. In addition, we apply an extended auto-encoder that maps the input (many CVs) onto a lower- dimensional latent space, used for the reconstruction of the input as well as the prediction of the committor [1]. I illustrate the method on simple but nontrivial toy systems, as well as extensive molecular simulation data of methane hydrate nucleation.
In the second part, I focus on a general framework of imposing known rate constants as constraints in molecular dynamics simulations, based on a combination of the maximum-entropy (MaxEnt) and maximum-caliber principles (MaxCal). Starting from an existing ensemble of (rare event) dynamical trajectories or paths, e.g. obtained from TPS, each path is reweighted in order to match the calculated and experimental interconversion rates of a molecular transition of interest, while minimally perturbing the prior path distribution [2]. This kinetically corrected ensemble of trajectories leads to improved structure, kinetics and thermodynamics. One also learns mechanistic insight that may not be readily evident directly from the experiments. This method does not alter the Hamiltonian directly, and therefore we recently proposed a novel MaxCal-based path-reweighting technique to optimize parameters in the molecular model it- self, while constraining kinetic observables [3]. This opens up the possibility to design molecular models that lead to desired kinetic behaviour.

[1] M. Frassek, A. Arjun, and P. G. Bolhuis, J. Chem. Phys. 155, 064103 (2021).
[2] Z. F. Brotzakis, M. Vendruscolo, and P. G. Bolhuis, Proc. Natl. Acad. Sci. 118, (2021).
[3] P. G. Bolhuis, Z. F. Brotzakis, and B. G. Keller, J. Chem. Phys. 159, 074102 (2023)
 

 

02.05.2024, 10h15-11h00

Speaker: Prof. Stijn De Baerdemacker, University of New Brunswick, Canada

Title: Interpretable Machine Learning in Quantum Chemistry

Room: R4

 

22.01.2024 (Monday), 14h15

Speaker: Thorsten Hansen, Københavns Universitet

Title: Electron transfer theory: A modern perspective?

 

17.01.2024 (Wenesday), 14h15

Speaker: Janus Juul Eriksen, Danmarks Tekniske Universitet

Title: Future Perspectives of Incremental Electronic-Structure Theory

 

10.01.2024 (Wenesday), 14h15

Speaker: Erik Donovan Hedegård, Syddanske Universitet

Title: Computational Bio-inorganic Chemistry

 

 

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24.11.2023 , 14h15 (cancel)

Speaker: Sondre Kvalvåg Schnell  

Title: TBA

 

17.11.2023 , 14h15

Speaker: An Ghysels, Ghent University, Belgium

Title: Estimating kinetics of processes with metastable states usiing advanced molecular dynamics simulations

 

10.11.2023 , 14h15

Speaker: Sarai Dery Folkestad 

Title: TBA

 

06.10.2023 , 14h15

Speaker: Alice Balbi

Title: Time-dependent coupled-cluster for ultrafast spectroscopy

 

27.09.2023 , 14h15

Speaker: Laura Grazioli from Mainz

Title: Challenges in the Calculation of Properties in a Magnetic Field, using Coupled-Cluster and Unitary Coupled-Cluster Theory

 

02.06.2023 , 14h15

Speaker: Eirik Kjønstad

Title: Geometric phase in coupled cluster theory

 

19.05.2023 , 14h15

Speaker: Melisa Mariel Gianetti

Title: Increasing friction with temperature: an unusual behavior

Abstract: 

In confined geometries, friction is affected by temperature, usually exhibiting a regular "thermolubric" behavior, with friction decreasing as temperature increases at microscopic scales. The reverse, namely friction increasing with temperature, is far less common, although it has been observed in specific situations.

In this talk I will introduce a recently developed model for zwitterionic monolayers, and I will describe our investigation on its tribological response to changes in temperature, applied load and sliding velocity by means of molecular-dynamics simulations. The main outcome of this work is a remarkable increase of friction with temperature. I will describe the explanation we found for this result, and I will also compare it to an analogous charge-free system.

I will also briefly introduce the aims of the SSLiP* project that brought me to the NTNU and which is my role within it.

*Scaling-up SuperLubricity into Persistence

 

28.04.2023 , 14h15

Speaker: Alexander Paul

Title: XAS of water clusters

 

21.04.2023 , 14h15

Speaker: Daniel Tianhou Zhang  

Title: Infinite Swapping & Asynchronous Path Sampling

 

31.03.2023 , 14h15

Speaker: Regina Matveeva   

Title: Particle-breaking Hartree-Fock theory for open molecular systems.

 

17.03.2023 , 14h15

Speaker: Rosario R. Riso  

Title: Chiral fields and molecules: Enantiodiscrimination and Stereoselectivity

 

10.03.2023 , 14h15

Speaker: Titus van Erp 

Title: Infinity-RETIS: Unlocking Exact Dynamics of Rare Molecular Events with Efficient Non-synchronous Replica Exchange Path Sampling

Abstract

Rare events, such as protein folding, chemical reactions, nucleation, and membrane permeation, are important molecular processes that cannot be studied using traditional Molecular Dynamics (MD) simulations due to their long timescales. To overcome this challenge, Transition Interface Sampling (TIS) has been developed [1], which uses Monte Carlo techniques to sample path ensembles in MD trajectory space and provides fast and exact information on the dynamics of rare events. The efficiency of TIS can be further improved by using Replica Exchange TIS (RETIS) [2], which executes replica exchange moves between path ensembles. However, RETIS is not easily parallelizable as MD trajectories have different lengths, leading to unbalanced CPU costs for Monte Carlo moves. The Infinity-RETIS method solves this problem by incorporating non-synchronous replica exchange techniques [3] and allows for an infinite number of replica exchange moves to be executed between standard MC moves without incurring significant computational cost. This method provides a highly efficient and parallelizable solution for studying rare molecular events and obtaining precise information on their dynamics.

References

[1]T. van Erp, D. Moroni, P. Bolhuis, The Journal of Chemical Physics, 118, 7762-7774 (2003) [2]T. van Erp, Phys. Rev. Lett., 98, 268301 (2007) [3]S. Roet, D. Zhang, T. van Erp, J. Phys. Chem. A, 126, 8878-8886 (2022)

 

17.02.2023 , 14h15

Speaker: Matteo Castagnola 

Title: Polaritonic response theory for exact and approximate wave functions

 

10.02.2023 , 14h15

Speaker: Sara Angelico 

Title: Coupled Cluster theory in Cavity Born-Oppenheimer approximation

 

03.02.2023 , 14h15

Speaker: Gaston Courtade  

Title: Combining experiments and simulations to understand multidomain proteins

 

27.01.2023 , 14h15

Speaker: Gunnar Lange 

Title: What can topology do for you?

Topological ideas have become increasingly relevant in physics, chemistry and material science in recent years. Topology can help explain existing experimental data, and can also guide and open new avenues of research.

In this talk, I will give a broad overview of topological ideas both in the context of my own research in band topology, and in a wider context. I will also discuss how light-matter coupling can impact topology, and vice-versa. 

 

13.01.2023 , 14h15

Speaker: Lu Xia 

Title: Interactions between point defects and internal interfaces in bismuth ferrite

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04.11.2022 , 14h15

Speaker: John Philbin fra UCLA, California

Title: From superradiant nanomaterials to ultracold molecules

 

28. October 2022 , 14h15

Speaker: Marcus Takvam Lexander

Title: Dynamics in QED Cavities

 

21. October 2022 , 14h15

Speaker: Tor Strømsem Haugland

Title: Application of computer aided derivation and code generation for CCSDT and QED-CCSD

 

17. October 2022 , 10h30

Speaker: Trond Saue, CNRS --- Université Toulouse III-Paul Sabatier

Title: Does chemistry need more physics?

 

14. October 2022 , 14h15

Speaker: Eirik Falck da Silva, SINTEF

Title: Applications of Computational Chemistry in Solvent Based Separations

 

07. October 2022 , 14h15

Speaker: Titus Van Erp

Title: Exchanging replicas with unequal cost, infinitely and permanently

Authors: Sander Roet, Daniel T. Zhang, and Titus S. van Erp

 

30. September 2022 , 14:15 

Speaker: Bendik S. Sannes

Title: Spin-adapted open-shell Coupled Cluster theory

 

23. September 2022 , 14:15 

Speaker: Lukas Baldauf

Title: A coarse-grained model for alginate hydrogels

 

24. June 2022 , 14:00 + Teams 

Speaker: Konrad Wilke

Title: : Investigation of the molecular mechanism of sodium chloride dissociation in water with rare event simulations

 

26. November 2021

Speaker: Sander Roet 

Title: ∞RETIS: hairy business

 

19. November 2021

Speaker: Regina Matveeva 

Title: Grand Canonical Hartree-Fock

 

12. November 2021

Speaker: Jocelyne Vreede, University of Amsterdam, Zoom meeting

Title: Sampling rare events in biomolecular systems

 

5. November 2021

Speaker: Rosario Roberto Riso  

Title: Fully consistent MO theory in QED environments

 

29. October 2021

Speaker: Prof. An Ghysels 

IBiTech – BioMMeda research group, Ghent University, Belgium

https://www.ugent.be/ea/ibitech/en/research/biommeda

Title: Permeability of small molecules through membranes from computer simulations

 

22. October 2021

Speaker: Alex Paul

Title: Efficient algorithms for coupled cluster with approximate triples for larger molecular systems

 

15. October 2021

Speaker: Daniel Zhang

Title: Path sampling and redox reactions