Second Annual TCCM Workshop-Leuven

 

The second year ITN-TCCM workshop took place this July 2017 in Leuven, a pretty university town 20 minutes by train from Brussels, Belgium. Our ESRs presented their second-year work in a four days conference held in the Katholieke Universiteit Leuven (KU Leuven), the largest and oldest university of the Low Countries and the oldest Catholic university still in existence. Host and organizer of the event has been Jeremy Harvey, full professor and head of the Quantum Physics and Physical Chemistry department at KU Leuven.

 

Day one, Monday 17th July:

As usual the morning was dedicated to the supervisory board, so that the real conference started in the afternoon with a talk by the first expert Shirin Faraji, associate professor in Theroretical and Computational Chemistry at the Zernike Institute, University of Groningen (The Netherlands), who introduced the audience to her most recent advances in her research topic: the development of hybrid classical/quantum dynamical methods for studies of light-induced processes and quantum effects in DNA, with particular focus on the role of photodissociation for light-driven DNA repair mechanisms . Afterwards the first student, Neus Aguilera, guided the spectator through her progress in modelling the deactivation mechanism of Nonsteroidal Antiinflammatory Drugs (NSAIDs) excited states. In order to understand the complexity of this mechanism the sample under investigation included a set of eleven different active principles, in gas phase and in solution. Neus’s work has prospected the actual possibility of building a model phototoxicity alert that will ultimately improve the assessment of the photophysical properties of drugs.

Martina De Vetta held the stage right after with her “Photosensitizers for photodynamic therapy: from photophysics to assisted delivery”, where she illustrated through her research the potential of liposomes as efficient and selective delivers of drugs, i.e. cancer drugs, a very hot and delicate point in scientific investigation.

 

Day two, Tuesday 18th July:

The morning session started with the presentation of the second expert, Stijn De Baerdemacker, postdoc at the Center of Molecular Modeling, Ghent University (Belgium). De Baerdemacker intoduced his newly discovered family of Antisymmetric Product of Interacting Geminals (APIG) states with mean-field like computational cost and the same accuracy as Doubly-Occupied Configuration Interaction (DOCI). At this point Giovanna D’Angelo showed how from smaller unsaturated hydrocarbon clusters in gas phase through high energy collisions with ions it is possible to induce a knockout which will lead to a molecular growth by means of combined experimental and theoretical evidences.

Afterwards, the singlet fission girl, Meilani Wibowo, elucidated how this process converts an excited singlet state into two (local) triplets that are coupled into a singlet, leading to the exploit of a high-energy photon that generates multiple electron-hole pairs. Such pairs, capable for charge separation, are the keys to improve the efficiency of organic solar cells.

Dmytro Ivashchenko entertained the audience with his project. First of all the ESR developed a script that allowed an extensive automation of the protocol nowadays in use to obtain molecules collision cross sections (CCSs) theoretically and recently he has been working on new atomic paramenters used by the CCSs determination software (MOBCAL). The combination of theoretical and experimental CCSs will permit a more reliable identification of a specific compound.

Enriko Skoruppa, a KU student, briefed on how DNA physical properties can be understood simply modeling them as polymers, which means neglecting its “chemical details”. He focused on how some experiments and theory discrepancies can be fixed by introducing a twist-bend coupling into the energy functional of the twistable worm-like chain (TWLC).

Before lunch Tommaso Francese discussed his discoveries in the magnetism field. The study concerns dithiazolyl (DTA)-based compounds, the best candidates for potential technological applications, like storage devices, sensors and quantum computers. The issues addressed will help providing a magneto-structural map as a function of the substituents of the DTA-moiety, that could be used as a practical tool to help experimentalists to design more stable and efficient purely organic radicals with ferromagnetic properties in the solid state.

After the lunch break Martin J. Paterson, the third expert, full professor and head of Dynamics and Structure research grouping at Heriott Watt University (The UK), addressed the audience with the last improvements of the Monte Carlo Configuration Interaction (MCCI) and some appropriate examples of its effectiveness and capabilities. Andi Cuko followed up with his Monte Carlo basin hopping (MCBH) studies elucidating the structure-properties relationship of oxide nanoparticles, in particular titania (TiO2) nanoclusters. The information gathered contains “signatures” of mixed titanosilicates in order to help experimentalists characterizing these structures.

“Networked computing for ab-initio modeling the chemical storage of renewable energy” by Carles Martí finally provided an insight on the modeling of non-reactive scattering processes of OH+H2 system using a new PES developed by the student, which increased the agreement with the experiments and simulating the developing of a more general Potential Energy fitting, called the Bond Order expansion fitting method, that would be able to predict the long range behaviour.

 

Day 3, Wednesday 19th July:

Celine Chizallet, expert 4 and doctor at IFP Energies nouvelles (France), got this day started unveiling the secret structures and roles of heterogeneous catalysts. Catalysts composed of sub- nanometric platinum particles dispersed on a gamma-alumina support are of common use in refineries. Prof. Chizallet presented the contribution of ab initio calculations to elucidate the physical-chemistry of these systems, and how it impacts the reactivity of the particles for alkane dehydrogenation paving the way for the introduction of ab initio kinetic data in kinetic models, to access macroscopic predictions thanks to a multiscale approach. After this, Ewa Szłapa caught people’s interest with her work on the hydroformylation of propene. She explained how the product-ratio depends on the reaction conditions (temperature, initial catalyst and propene concentrations and pressure of gases) and how the use of Density Functional Theory and explicitly correlated coupled-cluster methods for calculating PES have been crucial to give insights in the detailed reaction mechanism.

Francesco Talotta owned the stage with his trans-[RuCl(NO)(py) intramolecular NO linkage photoisomerization. The DFT and further ab initio CASSCF/CASPT2 calculations study shed light on the specific reaction mechanism. Francesco explained the importance of such an achievement and the need to impulse a follow-up study determining the most probable pathways along with the spin-orbit couplings responsible for radiationless transitions, being ruthenium nitrosyl complexes of great utility in a variety of applications, such as optical switches, data storage, and medicine.

Cyclacenes features have been the subject of Stefano Battaglia’s contribution. The ITN fellow investigated different properties such as the total position spread tensor (TPS) and the singlet-triplet energy gap (ST gap) as a function of the system size at different levels of theory, namely by a semi- empirical Hückel approach and by wave function theory. The obtained results show a decreasing ST gap and an increasing radical character with increasing system size.

Eliot Boulanger’s, postdoc at the Theoretical and Computational Chemistry Group of KU Leuven, talk discussed his new global optimized of the Lennard-Jones parameters for a large training set of molecules. Comparing the results to the original GAFF parameters, a significant improve of the prediction of the heat of vaporization is registered. Although a systematic underestimate of the free energy of solvation and leaded to a rescale of the water-compound interaction.

The last morning talk was Maria Izquierdo’s and concerned the modelling of a conjugated polymer with a fullerene derivative in bulk heterojunction architectures, predicted to be more efficient in organic solar cells. The student underlined how Density Functional Theory and its Time Dependent extension, coupled with the Discrete Reaction Field method as implemented in the Amsterdam

Density Functional modeling suite predicted organic-photovoltaic blends to be very promising for future applications.

The break recharged the battery for a presentation on vibronic couplings by Tohru Sato, associate professor at Kyoto University (Japan) and fifth expert invited. The professor introduced his recently proposed concept of vibronic coupling density (VCD) to analyse and control diagonal and off- diagonal vibronic couplings, crucial for the efficiency of emitting molecules, and how, on the basis of VCD analysis, efficient emitting molecules have been designed by the suppression of vibronic couplings in anthracene and triphenylamine, this last one being a non-emitting molecule.

The rest of the afternoon was concerted as an homenage to Prof. Arnout Ceulemans’s career in perspective of his, at time imminent retirement. As a consequence his last and brilliant PhD students gave interesting contributions aimed to enlighten the great influence Prof. Ceulemans’s knowledge and humanity had on their life and careers. The section concluded with a curious presentation by Prof. Ceulemans presentation named “Symmetry: unquestioned answers -unanswered questions”.

 

Day 4, Thursday 20th July:

Julien Michel, research fellow at the Royal Society University (the UK) and sixth expert, raised the presents’ attention towards the subject of ensemble-based drug design. The protocol developed allowed him and his collaborators to characterize cryptic ligand binding sites in proteins and predict ligand binding energetics.

Gabriele Dalla Torre later on raised the question: How toxic is aluminium? Increasing evidence shows it to have an actual toxic effect on biological systems and associates it to neurodegenerative diseases like Alzheimer. His state-of-art computational identification of the best combination Al(III)-ligand aims to help developing a more effective chelation therapy, which trapping the aluminium atoms would eliminate or reducing the toxic effect of the metal.

Maximilian Menger took over to describe his extension of a fully polarizable QM/MM scheme to analytic excited state gradients following a Lagrangian approach. The method is applied to study of formation and relaxation of the bright excited state of an organic dye (DAPI) intercalated in a DNA pocket. Maximilian discussed the results that indicate the non-negligible effect of polarization between the DAPI and DNA pocket, in determining the fluorescence properties of the embedded dye.

Prof. Robert J. Deeth, professor of computational chemistry and last invited speaker, intervened with an enjoyable presentation on coordination complexes of transition metal ions. How to treat these paramagnetic and electronically complex systems ? Deeth discussed the potential of Ligand field theory whenever combined with classical molecular mechanics  used to give information on the nuclei motion. The ligand field molecular mechanics combination, in fact, efficiently captures the important structural and energetic consequences of d-electron effects such as Jahn-Teller distortions and spin-state changes, but improvements through machine learning potentials fitted on quantum mechanical calculations can be added to the force field.

Last but not at all least ESR of the symposium, Jelle Vekeman, explored the interaction energies of graphene-X and X-X (X being mehane or H2) and fitted them with Improved Lennard- Jones type potentials in order to get a set of parameters describing the dispersion interactions of interest. Different values proceeding from different sets of parameters were produced aiming at producing potentials that are on one hand very accurate, but on the other easily compatible with molecular dynamics.

After the closing ceremony, the meeting continued for the ESRs with the brief-workshop “Project Management Course” by Berta Herrero, intended to be a basic introduction to project management that could turn up to be of great interest in the near future for aspirant scientists working in Companies, as well as employed in the University.

 

Giovanna D’Angelo

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