Wydział Fizyki UW > Badania > Seminaria i konwersatoria > Seminarium "Modeling of Complex Systems"

Seminarium "Modeling of Complex Systems"

2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025 | 2025/2026

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Prof. R. Przeniosło (IFD UW)

Analysis of Diffraction Peak Broadening as a Tool for Investigating the Crystal Structure Parameters of Materials

In studies of the crystal structure of materials using X-ray and neutron diffraction, one sometimes observes a significant variation in the widths of diffraction peaks. Two methods for the quantitative description of this distribution will be discussed.The first is a statistical approach — the so-called Anisotropic Peak Broadening Model [N.C. Popa, J. Appl. Cryst. 31, 176 (1998); P.W. Stephens, J. Appl. Cryst. 32, 281 (1999)].The second method involves constructing a crystal structure model with a symmetry different from that initially assumed.Both methods will be illustrated with examples from studies of several materials, such as chromium [Physica B 530 (2018) 183–190], oxides Fe₂O₃, Cr₂O₃, Ti₂O₃, Al₂O₃, V₂O₃ [Acta Cryst. B 74 (2018) 660–672], rutile TiO₂ [J. Phys. Chem. C 127 (2023) 19240–19249], and PbO₂ [Phys. Rev. B 103 (2021) 064109].

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).During the seminar the coffee and cakes are provided. Join Zoom Meeting
https://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1
Meeting ID: 963 7863 2993
Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr Katarzyna Młodzikowska (CENT, UW)

Challenges With Earth-Abundant Metals And How To Solve Them

The development of sustainable catalytic methodologies based on earth-abundant first-row transition metals represents a key challenge in modern chemistry. 1 In this talk, I will present our recent work demonstrating that a single pincer ligand framework can support iron, cobalt, and manganese complexes with remarkably diverse and well-defined catalytic reactivity.Using this versatile platform-pincer ligand- we have explored three distincttransformations across the metal triad (Figure 1). With iron, spin-state-resolved DFTanalysis combined with experimental studies revealed β-hydride elimination as the dominant deactivation pathway in alkene metathesis, and identified design principles to restore productive reaction. 2 With cobalt, two isostructural complexes differing only in their ancillary ligand (N₂ vs. methyl) exhibit orthogonal E/Z stereoselectivity in allyl ether isomerization, arising from fundamentally different mechanisms. 3 With manganese, the same pincer scaffold enables a highly efficient Michael addition ofunactivated aliphatic nitriles to α,β-unsaturated ketones. 4 These three examples illustrate that the choice of metal within the same pincerframework has profound consequences for both the reaction mechanism and the catalytic outcome. Spin-state control, ligand non-innocence, and the stability of key intermediates all play decisive roles, and understanding them is essential for the rational development of earth-abundant metal catalysts.

References:1. Bullock, R. M. et al. Using nature’s blueprint to expand catalysis with Earth-abundant metals. Science 369, eabc3183 (2020).2. Młodzikowska‐Pieńko, K. et al. Toward Iron‐Catalyzed Alkene Metathesis: Mapping the Reactivity and Deactivation Pathways of an Iron Metallacyclobutane. Angew. Chem. 137, e202515731 (2025).3. Garhwal, S. et al. Reversible 1, 2-Methyl Migration to an N-Heterocyclic Carbene in a PCNHCP Cobalt (I) Complex Enables Stereoselective (E and Z) Allyl Ether Isomerization. (2023).4. Dey, K. et al. Manganese‐Ketenimine Intermediates as Active Catalysts in the Michael Addition of Unactivated Nitriles to α, β‐Unsaturated Ketones. Angew. Chem. Int. Ed. 64, e202423275 (2025).

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr. Shafiq Ur Rehman (IFT UW)

Photocorrosion-Inhibited MoS2-Based Heterostructures for Stable Photoanodes in Neutral pH Overall Water Splitting”

Photocorrosion and chemical degradation are major challenges that limit the long-term stability of transition metal dichalcogenide (TMD) heterostructure-based photoanodes in aqueous environments, reducing their durability and catalytic efficiency during solar-driven water splitting. To address this issue, I systematically design and investigate hybrid photoanodes based on heterostructures formed from our previously identified stable monolayers (MoS2, WS2,PtSe2, PdSe2 and NiSe2)1. In this talk, I will present and discuss possible combinations of photocorrosion-resistant heterostructure-based photoanodes. Based on the promising monolayers, I focus on MoS2-based heterostructures, particularly MoS2/WS2 and MoS2/PtSe2, as potential photoanodes for water splitting under near-neutral pH conditions. Using first-principles calculations, thermodynamic stability analysis, and ab initio molecular dynamicssimulations under realistic operating conditions (temperature, pressure, and pH), I demonstrate that both heterostructures exhibit strong structural stability and intrinsic resistance to photocorrosion in aqueous environments near neutral pH. Electronic structure calculations reveal type-II band alignment that promotes charge separation, alongside low overpotentialsfor the hydrogen and oxygen evolution reactions (OER), with the OER proceeding spontaneously on MoS2/PtSe2 at neutral pH. The corresponding solar-to-hydrogen efficiencies reach up to 12.3% for MoS2/WS2 and 14.5% for MoS2/PtSe2, establishing these co catalyst free, bifunctional photoanodes as promising candidates for durable and efficient water splitting in near neutral aqueous environments.References:S. U. Rehman, J. W. Wang, G. Wu, J. Xian, N. Mahmood, Unraveling the photocatalytic potential of transition metal sulfide and selenide monolayers for overall water splitting and photo-corrosion inhibition, J. Mater. Chem. A, 2024, 12, 6693–670.

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).During the seminar the coffee and cakes are provided.
Join Zoom Meeting
https://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1
Meeting ID: 963 7863 2993
Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr. Meysam Bagheri Tagani, (University of Guilan, Iran)

Symmetry‑Driven Topological Phases in Au₂Ge and Kagome Goldene

Two‑dimensional materials with symmetry‑protected electronic structures provide a fertile platform forexploring unconventional quasiparticles and topology‑driven quantumphenomena. In this talk, I will present our recent advances in engineeringand understanding Dirac nodal‑line fermions and flat‑band physics ingold‑based 2D systems. I will first discuss the monolayer Au₂Ge, where mirrorsymmetry protects a Dirac nodal line encircling the Γ point. By tuning thetwist angle between the monolayer and the substrate, we demonstrate acontrollable topological transition driven by symmetry breaking. I willthen introduce our latest work on kagome goldene, a single‑atomic‑layerkagome lattice realized through line‑graph epitaxy. This system hosts anearly flat band, van Hove singularities, Dirac cones, and—throughproximity to Au₂Ge—dual Dirac nodal lines. STM/STS measurements combinedwith first‑principles calculations reveal how geometry, stacking, and edgetermination govern the electronic states in this elemental kagomematerial.

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).
During the seminar the coffee and cakes are provided.
Join Zoom Meeting
https://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1
Meeting ID: 963 7863 2993
Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Prof. Keith Butler (UCL, UK)

Learning the Language of Crystal Chemistry: Using Concepts from Natural Language to Model Solid State Chemistry

The discovery and design of new materials is critical for advancing carbon-emission reducing technologies such as renewable energy and electric vehicles. Experimental discovery of new materials is typically slow and costly, quantum mechanics (QM) calculations have brought computational materials design within reach. However, QM calculations are often limited to relatively small sets of materials, as their computational costs are too great for large-scale screening, this is the case for calculating properties required for new energy materials. In this talk I will present examples of how we have been adapting concepts from language models to help with building fast and efficient models for materials properties. I will show how we can learn distributed representations of atomic species directly from large databases of crystallographic structures [1, 2]. I will also show how a large language model trained on crystallographic data can help to solve one of the outstanding challenges of solid-state chemistry; the prediction of structure from chemical formula [3].[1] npj Comput Mater 8, 44 (2022)[2] APL Machine Learning 2, (2024)[3] Nature Commun. 15, 10570 (2024)

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).
During the seminar the coffee and cakes are provided.
Join Zoom Meeting
https://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1
Meeting ID: 963 7863 2993
Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

(IFT UW)

student's talks

The seminar will consist of student presentations (six talks, ~15 min each) and will therefore run slightly longer than usual (~1.5 h). The list of presentations is provided below:
1. Gustaw Daniel: "The Byte Latent Transformer (BLT) in LLM."
2. Piotr Psuty: "Investigation of cation positions in the structure of selected zeolites based on X-ray powder diffraction"
3. Ulkar Jabbarli: "Electronic band structure engineering of ScB and its thermoelectric and optoelectronic properties."
4. Maciej Szyszko: "Impact of dopant concentration and structural arrangements on the optoelectronic properties of 2D Mo₁₋ₓWₓ".
5. Karol Gałazka: "Ab initio investigation of electronic properties of Cl-doped CrSBr."
6. Piotr Marczak: "LUXE: QED, axions and my camels."

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).During the seminar the coffee and cakes are provided. Join Zoom Meeting
https://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1
Meeting ID: 963 7863 2993
Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Joanna Jankowska (Faculty of Chemistry, UW)

Towards real-time simulations of slow inter-electronic-state transitions

Theoretical modeling of very slow nonadiabatic processes, occurring onnanosecond and longer timescales, remains challenging due to theextremely high computational cost, placing them beyond the reach oftraditional real-time nonadiabatic dynamics propagation methods. At thesame time, while reaction-rate theories of varying complexity cansometimes be used to estimate relevant timescales, they often struggleto describe processes in which vibronic and other out-of-equilibriumstructural effects play an essential role.Recently, our group has developed a new nonadiabatic molecular dynamicsscheme designed to describe long-time photophysical processes – such asinternal conversion, intersystem crossing, reverse intersystem crossing,and fluorescence – within a unified framework based on the classicalpath approximation (CPA). The approach combines finite-temperaturequantum-classical molecular dynamics using cost-efficientelectronic-structure methods with higher-level molecular propertysampling and classical stochastic-matrix probability propagation. Whileoriginally motivated by the complex excited-state behavior ofmultiresonance TADF emitters, the method proves applicable more broadlyto photoinduced charge-carrier dissociation and migration in selectedorganic photovoltaic systems. In this seminar, I will discuss thetheoretical foundations of the approach, its range of applicability, andillustrative examples from both light-emission andsolar-energy-conversion contexts.

The seminar will be held in hybrid mode: in room 1.40 (FUW, Pasteura 5).During the seminar the coffee and cakes are provided. Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1Meeting ID: 963 7863 2993Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr. Karolina Milowska (Ikerbasque Research Fellow, CICnanoGUNE)

Fundamental Transport Mechanisms in Disordered Nanostructured Networks

Understanding magnetotransport in disordered quantum materials remains a major challenge in condensed matter physics. A variety of models — quantum interference, variable‑range hopping, weak or fluctuation‑induced tunnelling, and hybrid metallic‑insulating frameworks — are frequently used to interpret magnetotransport in disordered systems, yet no unified theory can reliably describe observations across all materials. Carbon nanotube (CNT) networks provide an ideal testbed for this problem: their electronic character can be tuned from metallic to semiconducting or semimetallic simply by changing chirality, while their hierarchical structure captures the complexity of real nanostructured conductors.In this talk, I will discuss our recent progress in unifying experiment and theory to uncover the fundamental transport mechanisms in disordered nanostructured networks. Using ultrahigh-field magnetotransport experiments (1.5K-300K & up to 60 T) performed at the Los Alamos National Laboratory, we identified a crossover from metallic to semiconducting-like behavior in CNT fibers and films, MR sign reversals, non-monotonic temperature dependences, and low-T plateaus indicative of fluctuation-assisted transport [1]. To interpret these findings microscopically, we developed a new multiscale magnetotransport modelling paradigm that combines quantum-coherent tight-binding transport calculations (TB-NEGF), external magnetic field effects via Peierls substitution, and Molecular Dynamics (MD) simulations. This framework reproduces the experimental trends and reveals how inter-tube tunnelling, defect scattering, and quantum interference shape magnetoresistance across junctions, bundles, and complex looped geometries, guiding the design of advanced magnetoresistive composites. Together, the combined experimental–theoretical approach demonstrates that even macroscopic CNT conductors are ultimately defined by quantum interference at the nanoscale. The insights gained establish design principles for tuning conductivity and magnetoresistance in nanocarbon networks and other disordered quantum materials.[1] J. Bulmer, C. Kovacs, T. Bullard, C. Ebbing, T. Haugan, G. Pokharel, S. D. Wilson, F. F. Balakirev, O. A. Valenzuela, M. A. Susner, D. Turner, P. Fu, T. Kulka, J. A. Majewski, I. Lebedeva, K. Z. Milowska, A. Lekawa-Raus, M. Marganska “Adjudicating Conduction Mechanisms in High Performance Carbon Nanotube Fibers” arXiv:2507.20481

The seminar will be held in hybrid mode: in room 1.40 (IPC PAS).During the seminar the coffee and cakes are provided. Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1Meeting ID: 963 7863 2993Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr. Kevin Rossi (TU-Delft)

Modelling materials complexity

Materials shape modern day technologies, from energy storage and production to microelectronics. Materials' performance emerges from intricate structure–process–property relationships that are difficult to unravel. This talk highlights two cases-studies how machine learning helps navigate such complexity. I will first show how ML enables reliable single-atom detection in microscopy images, revealing subtle structural motifs that govern material stability. I then present how data-driven models capture structural rearrangements in nanoparticles with application in catalysis, providing insight into dynamics that are otherwise hard to observe or simulate. I will then conclude with a personal perspective on the need for a holistic materials-innovation framework that integrates complexity across different scales.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr hab. Mateusz Goryca (FUW)

“How to study magnetic monopoles?”

In particle physics, a magnetic monopole remains a hypothetical elementary particle that has never been observed. However, certain condensed matter systems can contain effective magnetic monopoles. One of such systems are Artificial Spin Ices (ASIs) arrays of interacting nanomagnets that have allowed the design of geometrically frustrated exotic collective states not found in natural magnets. A key emergent description of fundamental excitations in ASIs is that of mobile quasiparticles that carry an effective magnetic charge  that is magnetic monopoles. These charge excitations can interact with each other and with applied magnetic fields via the magnetic analog ofthe electronic Coulomb interaction, representing the emergence of a range of novel phenomena, including the possibility of "magnetricity" – magnetic analog of electricity. While the presence of monopoles in ASI has been observed in pioneering imaging measurements, dynamical studies ofmonopole kinetics, and (especially) the ability to tune continuously through monopole-rich regimes in thermal equilibrium, remain at an early stage.In the seminar I will present a noise-based experimental approach that we have developed to passively "listen" to spontaneous magnetization fluctuations in archetypal, thermally active square ASI. The experiment, supported by standard Glauber Monte-Carlo simulations, reveals specificregions in the magnetic field-dependent phase diagram where the density of mobile monopoles increases well over an order of magnitude compared with neighboring regimes. Moreover, detailed noise spectra demonstrate that monopole kinetics are minimally correlated (i.e., most diffusive) inthis plasma-like regime. Experiments and Monte-Carlo simulations of more complex ASIs (including quadrupolar and vertex-frustrated Shakti and Tetris lattices) show similarly fascinating behavior, revealing surprisingly rich field-dependent phase diagrams of these systems. The discovery of on-demand monopole regimes with tunable kinetic properties opens the door tonew probes of magnetic charge dynamics and provides a new paradigm for the studies of magnetricity in artificial magnetic materials.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr Tomasz Skóra (IFT UW)

Multiscale modeling and biological complexity: insights into microtubule dynamic instability

The teleonomic criterion, proposed by complexity scientist David Krakauer, defines complex systems by their ability to gather and process information to pursue goals. This criterion distinguishes complex systems from "simple" causal ones. It can be argued that the collective network of microtubules (MTs), which constitutes a part of the cytoskeleton, along with MT-associated proteins, meets this criterion. The mitotic spindle, for instance, is a goal seeking protein machine made of MTs that accurately locates, captures, and separates chromosomes during mitotic division. This complex behavior is rooted in the MT feature of dynamic instability — an abrupt, stochastic switching between polymerization and depolymerization.A complete molecular explanation for this phenomenon remains elusive. Moreover, much of the conventional understanding invoking changes in tubulin monomer shape upon GTP hydrolysis conflicts with recent experimental results. To address this gap in knowledge, we applied a multiscale modeling approach that combines high-resolution and coarse-grained computational methods to investigate MT tip structure and dynamics. Our work employs two complementary strategies:1. High-Resolution Dynamics: We performed exhaustive 4-microsecond all-atom molecular dynamics (MD) simulations of a 224-protein MT plus-end tip.2. Coarse-Grained Dynamics: We used two distinct coarse-grained approaches:(i) Iterative Boltzmann Inversion to parameterize a protein-resolution model and extrapolate the behavior of the MT plus-end tip using Brownian dynamics;(ii) data-driven "equation-free" approach to extend the all-atom MD trajectories to an unprecedented 6 microseconds.Our results confirm that both GDP- and GTP-bound MT tips exhibit an outward bending of protofilament clusters into characteristic ram's horn-like structures. Crucially, our results expose subtle yet important differences between the two nucleotide states that align with experimental cryo-ET images. However, whether these subtle differences are sufficient to fully explain MT dynamic instability remains an open question.

The seminar will be held in hybrid mode: in room 1.40 (IPC PAS) Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1Meeting ID: 963 7863 2993Passcode: 569551

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Mathias Boström (ENSEMBLE3, Warsaw, Poland)

Semi classical electrodynamics and Casimir effect

One thrust of my talk will be to explore how Casimir (van der Waals) energies potentially impact geophysical systems such as the buoyancy of CO2 gas hydrate clusters in the ocean on Enceladus (moon on Saturn) and the chemical composition of the E-ring of Saturn. Notably, Casimir effects have been indicated to have a role on water condensation on soil particles and on forces between surfaces. As the main reason for giving this talk is to explore potential collaborations with researchers from University of Warsaw I will try to give a broad overview of my work. My NCN funded Polonez bis-3 project at Ensemble3 (Warsaw) is approaching its end so I also want to highlight some of the research achievements from my team. One example system that I will discuss is our work enabling tuning of Casimir attraction/repulsion transitions between a polystyrene sphere (e.g., freely levitating or attached to an atomic force microscope tip) near a Teflon surface in a magnetic fluid mixture. Notably, the stable and measurable trapping distances can be manipulated by several orders of magnitude entirely by changing the zero-frequency transverse electric contributions to the Casimir force. In the past, this magnetic contribution to the Casimir-induced trapping has not been studied separately.

The seminar will be held in hybrid mode: in room 1.40 (IPC PAS) Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1Meeting ID: 963 7863 2993Passcode: 569551During the seminar the coffee and cakes are provided. The abstract of the talk is given below.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr Mateusz Wlazło (CENT, UW)

Theoretical description, recent results and perspectives in charge carrier dynamics phenomena in photoexcited hybrid nanojunctions from 2D-0D to 2D-2D

In molecular donor-graphene acceptor heterojunctions, a number of donor de-excitation pathways can lead to either charge or energy transfer from the 0D localized donor to the 2D-extended systems. We focus on nanographenes adsorbed on graphene, where the delocalization length of partially extended orbitals is influenced by both nanographene size (number of fused rings) and symmetry. As such, nanographene/graphene junctions provide an ideal platform for examining how these structural factors impact the competition between charge and energy transfer processes.To explore these dynamics, we analyze several ground-state properties – such as density of states, charge difference distribution, and interfacial interaction energy – to assess their predictive potential for transfer rates. Transfer rates are evaluated using Marcus theory for charge transfer and Förster theory for energy transfer. Our findings indicate that photoinduced hole transfer is the primary process in smaller, C3-symmetric nanographenes, while the Förster mechanism becomes increasingly relevant in larger nanographenes with reduced symmetry.Applying Förster theory, we examine the distance-dependence of energy transfer rates. Unlike the typical R^-6 dependence seen in localized dipole-dipole interactions, we observe a deviation indicative of delocalized charge densities in nanographene-graphene systems. Specifically, the nanographene energy transfer rate decays with a R^-4 dependence. As nanographene size increases, this dependence gradually softens, approaching the R^-2 law, characteristic of two fully extended 2D-2D systems. This trend suggests a crossover size limit, beyond which nanographenes should no longer be considered quantum dots but rather as π-extended systems, forming a distinct type of interface with graphene.

Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 15:15

Dr. Grzegorz Łach (IFT UW)

Entropy of water clusters and ices?

Water has many properties unusual for such a simple moleculeand among them is the large number of thermodynamically stable solidforms (ices) it can form. Most of the ices exhibit partial or completeproton disorder — while oxygen atoms form a translationally invariantlattice the positions of protons can assume one of macroscopic number ofconfigurations. The enumeration of these microstates is (in 3D) anunsolved computational challenge and I will present a new approach tosolve it.

The seminar will be held in hybrid mode: in room 1.40 (IPC PAS) Join Zoom Meetinghttps://uw-edu-pl.zoom.us/j/96378632993?pwd=MVgdPR80oKaE4pjLufb2NCtg6ql4Ax.1Meeting ID: 963 7863 2993Passcode: 569551