Title Promoter Affiliations Abstract "Development and application of reactivity force field for multiscale study of nanomaterials based on boron element." "Minh Nguyen" "Quantum Chemistry and Physical Chemistry" "Although molecular dynamics simulations are important techniques in theoretical studies of materials, no reliable force fields are actually available for treatment of the clusters of the elements. Our main objective is therefore to develop a set of highly accurate reactivity force fields and to apply them to multiscale studies of nanomaterials based on boron. The nanomaterials considered include medium and large-size atomic clusters and bulk-materials such as nanotubes, boron sheets and cage-formed fullerenes. To improve the fundamental physicochemical properties and applicability of these materials, impurities such as alkali and 3dtransition metals will be introduced into host materials. The doped materials having high stability will further be studied for applications in sequestration of CO2, capture and storage of small industrial gases and catalysts for chemical reactions. To achieve these purposes, three specific objectives can be elaborated as follows. The first objective of the project is to generate sets of parameters of reference structures by using highly accurate quantum chemical calculations. The second goal is to subsequently develop reactivity force fields (ReaxFF) derived from the QC calculations. The final goal of this project is to study the boron-based nanomaterials having specific chemical, optoelectronic properties… by using multi-scale simulation methods. The effects of alkali and 3d-transition metals to geometrical, electronic, magnetic, stability of impure boron clusters (BnM) containing up to hundreds atoms will be systematically investigated. We will provide elements of answer to the question of how the impurities affect the physicochemical properties, and the use of the resulting mixed clusters and coated bulk-materials in different technological applications." "Application-driven automated ReaxFF force field parameterization" "Toon Verstraelen" "Department of Physics and astronomy" "Molecular simulations are a fast and affordable alternative to experiments in physics and material science and chemistry. However, empirical models in simulation software are limited in terms of predictive accuracy. This project focuses on the development of an optimization suite, ParAMS, to improve the accuracy of computational models. It is demonstrated with applications to ReaxFF and density-functional tight binding." "SRP-Onderzoekszwaartepunt: Understanding, predicting, and tailoring molecular and material properties and reactivity through combined conceptual and computational quantum chemical approaches" "Frank De Proft" Chemistry "The study of chemical reactions and the development of novel compounds and materials is at the heart of Chemistry. The chemists’ rationalization of the what, how and why have taken a huge leap forward when chemical concepts were introduced. Particularly chemical concepts derived from quantum mechanics, and more specifically density functional theory (DFT), merit special attention, not only because they are fundamental in nature but also because they are computable by first principle quantum chemical methods. Therefore, the characterization of compounds can be treated on an equal footing, an invaluable trait if one wishes to establish guiding principles in the design of new fascinating molecules. At the same time, the almost exponential growth in computing power in combination with the availability of more accurate quantum chemical and computational chemistry methods offers chemists the possibility to directly evaluate the system’s target properties and reactivity. With this proposal, a unique combination of two complementary approaches is laid out through the synergistic interplay of conceptual and computational chemistry. With chemical concepts at the heart, we will engage in the study and understanding of chemical reactivity as well as molecular and material properties, on the one hand, and the design of high-potential compounds and unprecedented reaction networks, on the other hand. Next to applications in different fields of chemistry, we also continue to focus on the further development of the fundamental aspects. In addition, our expertise on DFT based concepts will be coupled with two core methodologies relatively new to our research group: artificial intelligence and multiscale modeling. We aim at advancing the field of conceptual quantum chemistry in new directions by considering complex environments, new ways of activation chemical reactions, extending the theory to excited states, and using concepts as the driving force for compound and reaction network exploration. The envisaged challenging applications involve molecular electronic devices, molecular switches, organic redox-flow batteries, and nano- and biological materials’ phenomena. Advances in these topics can be highly valuable for technology innovation, environmental sustainability and even reshaping society." "Reparameterization of ReaxFF force fields using sensitivity analysis and a novel global optimization approach (AutoCheMo)" "Toon Verstraelen" "Department of Physics and astronomy" "A novel approach to global optimization is introduced for high-dimensional, expensive, and black-box optimization functions (like the reparameterization of ReaxFF force fields). Our method of optimization interference and management is shown to identify more and better minima than traditional approaches. We couple this approach with a state-of-the-art sensitivity analysis to reduce the dimensionality of the problem and speed-up the procedure.  " "Apps for cops: a realist evaluation of the impact of mobile information technology on police decision-making and on police-citizen interactions" "Jeroen Maesschalck" "Leuven Institute of Criminology" "Police services have increasingly embraced digitalization in recent years, and the offered technologies have become more sophisticated. The digitalization of the police is a frequently discussed topic in academic literature as well. While there is already a considerable amount of research on the impact of various technologies, this primarily focuses on their impact in terms of performance (e.g. effectiveness or efficiency). Much less is known about the impact of technology usage on the daily decisions made by police officers and how this translates into their daily interactions with citizens. This research aims to address that lacuna by analyzing the use and impact of one specific technology, namely ‘mobile information technology’ (including the ‘Focus app’ used by the Belgian police). Mobile information technology (hereafter MIT) enables police officers to access a wide range of information (e.g. databases, hotspot lists) and to fulfill reporting requirements (e.g. generating police reports) directly in the field, all using a mobile device (such as a smartphone, tablet, or laptop). Specifically, three research questions were formulated, referring to successive steps in a chain:To what extent do police officers use MIT?If police officers use MIT, what is the impact of that usage on police decision-making?If the use of MIT has an impact on police decision-making, how does that impact translate in the interaction between police officers and citizens?Previous empirical research on the use of technologies, specifically MIT, has yielded conflicting findings regarding its impact. For instance, various studies have observed that MIT leads to time savings for police officers (e.g. Greenberg, 2017), while this was not confirmed in other studies (e.g. Carter et al., 2016). A clear explanation for these contradictions has largely remained absent. What sets this research apart is its focus on explaining such discrepancies, using the research strategy of 'realist evaluation' (Pawson & Tilley, 1997). More specifically, the study zooms in on differences in the context in which MIT is implemented ('contextual factors') and variations in the configuration and implementation of MIT ('intervention modalities') that could explain differences in use and impact ('outcomes'). All these components are brought together in 'context-intervention-mechanism-outcome (CIMO) configurations. This leads to a fourth research question:What role do contextual factors and intervention modalities play in the usage and impact of MIT?To answer the research questions, several hypotheses (theoretical CIMO configurations) were first formulated based on academic literature. These theoretical CIMO configurations were then tested and refined multiple times in the empirical research. Various forms of empirical data were collected in three local police forces in Belgium. Belgian local police forces were a good choice since the national rollout of a new MIT, namely the 'Focus app,' had just begun at the start of the doctoral research. The CIMO configurations were refined a first time based on qualitative data collected in two pilot case studies (two local police forces that were not included as cases in the actual data collection). With this knowledge, an online survey was developed and administered to the chiefs of the local police forces in Flanders and Brussels to select the three actual cases. Both in the two pilot cases and the three actual cases, the data collection methods consisted of a combination of interviews (11 in the pilot cases and 39 in the actual cases) and field observations (11 shifts in the pilot cases and 86 shifts, totaling 688 hours, in the actual cases). Specifically, respondents from the traffic, community and patrol departments were involved in the three actual cases. Case 2 also included the police forces’ 'project teams', which work primarily proactively to address various forms of disturbances. In total, ten services were thus involved. A within-case and across-case data analysis approach was performed, comparing the police forces, the selected departments, and, where relevant, the individual police officers. This allowed for an assessment of the role of variable contextual factors and intervention modalities.Regarding the first research question (which focuses on the extent to which police officers use MIT), we can broadly conclude that MIT was frequently used in all included departments. However, in most departments, police officers still relied regularly on the alternatives that existed before MIT was introduced. For example, in most departments, database inquiries were still conducted through the control room, and reporting requirements were often (in some departments, still as a standard practice) fulfilled at the office. The thesis provides a detailed description of the circumstances in which police officers chose to use or not use MIT. Various contextual factors, intervention modalities, and mechanisms were identified to help explain those choices. For instance, MIT was only used for reporting in departments where reporting through MIT could be easily handled with standard texts (intervention modality) or in services where on-site reporting was mandatory (contextual factor).To address the second research question (aimed at examining the impact of MIT usage on police decision-making), three aspects were considered. First, it was investigated to what extent MIT distracts police officers from what is happening around them. A distinction was made between distraction during patrolling and distraction during actual interventions. Concerning the first aspect, it was found that police officers frequently accessed the Focus-app during patrolling, potentially causing them to miss events happening around them. The frequency of this distraction varied significantly between departments. For example, the Focus-app was used more frequently in services where the device was mounted at the front of the vehicle. Regarding the second aspect, it was observed that in most departments, police officers often used MIT during interactions with citizens, which did indeed lead to distraction. However, police officers typically worked in pairs, and only one of them used MIT, allowing the other officer to focus on the situation and the citizen.Second, it was expected that the capabilities provided by MIT would motivate police officers to take certain actions more frequently. This expansion of actions is referred to as ‘netwidening’, which means broadening the scope of an individual police officer's surveillance net. Specifically, it was examined whether netwidening could be observed with regard to four decision points: the decision to 1) conduct a database inquiry, 2) perform a police stop, 3) engage in proactive patrolling, and 4) issuing official police reports for an offense. Concerning the first two decision points, it was found that, except for three departments (namely the community officers in cases 1 and 2 and the patrol department in case 3), police officers indeed conducted more database inquiries and person stops using MIT. Generally speaking, MIT made police officers less hesitant to conduct inquiries (and person stops) compared to when they had to burden the control room. The ease of using MIT also seemed to lead to reduced reflection on the necessity of the inquiry. Inquiries were often conducted ‘just to be sure’ or to make an initial assessment of whether a police stop would be worthwhile. Regarding vehicle stops, the ability to easily look up license plates (and then proceed to check the owner and the likely driver) before conducting a stop, actually led to more reflection on the necessity of a physical stop. The information from the inquiry was used to assess whether a physical stop was desirable, resulting in netwidening for inquiries but not for the actual interaction with the citizen. Another finding related to police stops was that in cases 1 and 2, MIT led to fewer registrations of these stops. Before the introduction of MIT, every interaction was recorded as soon as a database inquiry was requested through the radio channel. With field officers now able to do their inquiries themselves, registrations only occurred when the police officer deemed it necessary. The threshold for when registration was needed varied among respondents. In case 3, proactive stops were not always registered even before the introduction of MIT. Concerning the third decision point, the decision of where to patrol, it was expected that MIT would be used by supervisors to direct patrols to specific locations. In all three actual cases, MIT was indeed used for patrol assignments. In some departments, the assigned tasks were carried out in addition to the officers' regular patrols, resulting in netwidening, as more patrols were conducted than before the introduction of MIT. In other departments, patrols were limited to the assigned tasks, resulting in geographical netnarrowing. The time spent on patrols in those departments remained the same but was mostly limited to the locations on the assignment list. Regarding the decision to issue official reports for offenses, the ease of doing so in the field with MIT led some respondents to state that they did so more frequently. Others reported that MIT had no impact on their decision to issue official reports. Interestingly, the six respondents who indicated that MIT led to netwidening came from six different services across the three cases, indicating that no relevant contextual factors at the force or department level could be identified. Those who cited administrative burdens as a factor in their decision to issue official reports confirmed this form of netwidening. In summary, the assumption regarding netwidening was partially confirmed but not for all examined decision points.Third, it was expected that, as a result of their autonomous access to database information, police officers would base their decisions more on 'bureaucratic' database information and less on 'incidental' information (visible elements of the situation, e.g. behaviors, physical characteristics). This type of decision-making, based on knowledge of previously observed criminal or suspicious behavior, is referred to as 'bureaucratic suspicion' (Matza, 1969). For each observed decision point, it was examined whether there was (partially) bureaucratic suspicion and whether it was a result of MIT. The latter was deemed not to be the case if the police officer could have obtained the bureaucratic information consulted via MIT through the control room as well. For the decisions to conduct a police stop, register a police stop, search a person, and search a vehicle, it was indeed found that as a result of the availability of MIT, these decisions were more frequently (partially) based on information from databases than before. Thus, for these types of decisions, there does appear to be an increase in bureaucratic suspicion. The decision to conduct a drug test was also often (partially) based on bureaucratic information, but in most cases, the police officer would have obtained that information through the control room as well. Further, the decision to issue an official report for an offense and the decision to conduct an alcohol test were primarily based on incidental suspicion in most cases.To answer the third research question regarding the impact on police-citizen interactions, seven dimensions of interaction were identified, inspired by Della Porta and Fillieule (2004), which were expected to be influenced by the use of MIT, namely: (1) increased likelihood of interaction - decreased likelihood of interaction, (2) harsh - soft, (3) reactive - interventionist, (4) little communication - much communication, (5) strict - flexible, (6) fast - slow, and (7) cautious - incautious. Diverse effects were observed on each of these dimensions depending on how MIT was used.This research contributes to the academic literature by providing empirical support for two important assumptions regarding the potential impact of police digitization. Both the assumption that MIT would lead to netwidening and the assumption that it would lead to bureaucratic suspicion were confirmed but also nuanced by the data. In this way, the research results in an empirically grounded theoretical framework that provides insight into the impact of MIT in different circumstances. This theoretical framework is also relevant to practice since the final, empirically grounded, CIMO configurations allow policymakers to consider which circumstances they should take into account when aiming to achieve a particular outcome (or not). In addition to these specific recommendations, the research also yields some important findings that call for reflection. For instance, the finding that MIT leads to less information being recorded in formal databases is not without risk. It was observed, that information is either not recorded or recorded in more informal databases created within MIT (e.g. in briefing items). This can result in information being lost, and it may also lead to information overload for field officers, making it impossible for them to review all the information. The non-registration of proactive police stops means that neither supervisors nor colleagues are aware that a stop has taken place. It also implies that police officers no longer offer the written justification they typically had to provide for the stop. Moreover, the observation that the additional information provided through MIT is only rarely consulted during an inquiry, raises questions about the necessity of maintaining and offering such a large amount of information. If police officers often do not have the time to search for information in these modules themselves, perhaps the most relevant information should be pushed to them. Given the finding that the ease of using MIT reduces reflection on the necessity and legality of certain actions (e.g. database inquiries or police stops), it is important to encourage police officers to keep reflecting sufficiently about these actions. Oversight mechanisms can provide a potential solution, but they should not discourage the proper use of MIT. What seems more important is a supportive approach that teaches police officers to handle this increased autonomy.Finally, the observation that police officers appear to base many decisions on database information also calls for reflection. This confirms the need for high-quality, up-to-date databases. Moreover, the Belgian legal framework currently mainly refers to incidental grounds for many actions. For instance, administering a drug test must be justified by reference to visible signs of drug use. 'Being known in the police databases' is not included as a criterion to justify a drug test. Similarly, for other police powers (e.g. searching a person or a vehicle), being known in the police databases can generally only be considered a legal reason in combination with incidental elements that justify the search for information about someone's criminal history. Police officers seem to be aware of these limitations, as they appeared to omit the bureaucratic elements on which their decisions were based in their written justifications. The growing role of information from databases also raises normative questions. There is a risk not only of overpolicing based on visible elements and thus incidental suspicion (which currently receives much attention, particularly in the debates about ethnic profiling) but also based on registered data from the past and thus bureaucratic suspicion." "Multi-scale Simulations of Dynamics of Chemical Reactions" "Jeremy Harvey" "Quantum Chemistry and Physical Chemistry" "The motions of the chemical environment, such as solvents and proteins, are closely connected to the kinetics and dynamics of reactions. The environment can either perturb reaction pathways by altering the free energy of activation and reaction, or exert a dynamical role by affecting the motions of reacting species during barrier-crossing and energy exchange processes. Theoretical calculations and molecular dynamics simulations have made it possible to obtain a direct evaluation of the effect of the chemical surroundings. Nevertheless, owing to the sophisticated interaction patterns and motions at different time scales, it is often a challenging task in computational chemistry to get a clear picture of how the surroundings are coupled to the reaction progress, and how they damp the nuclear dynamics. The main objective of this PhD thesis is to understand the effect of chemical environments (including solvents and protein) on reactions by developing efficient reactive force fields and using them in molecular dynamics simulations. This thesis has explored three classes of chemical phenomena, (i) energy relaxation of deuterium fluoride in deuterated acetonitrile and dichloromethane (Chapters 3 and 4), (ii) dynamics of the Diels-Alder reaction in organic solution (Chapter 5) and (iii) mutation effects on the Co—C bond cleavage step in adenosylcobalamin-dependent glutamate mutase (Chapter 6). " "Atomistic simulations of plasma-enhanced chemical vapor deposition of single walled carbon nanotubes" "Erik Neyts" "Plasma Lab for Applications in Sustainability and Medicine - Antwerp (PLASMANT)" "Single walled carbon nanotubes (""SWNTs"") are hollow cylindrical structures consisting of a hexagonal carbon network. Their unique properties, such as extreme strength, very high thermal conductivity and structure dependent bandgap, offer perspective on various applications, in e.g. nanoelectronics, as chemical sensors or as induced field emitters. Such applications, however, require precise control over fundamental properties of the SWNTs. This control is currently lacking. Especially control over the chirality of the SWNT, which is directly responsible for the bandbap, is desired. Plasma-enhanced chemical vapor deposition (""PECVD"") is regarded as one of the most promising deposition tools to accomplish this control. However, the underlying fundamental growth mechanisms are largely unknown. In this project, we therefore wish to investigate various PECVD-specific processes and process parameters in order to gain insight in the growth mechanisms, aiming at gaining control over the resulting SWNT properties. We wish to accomplish this goal by using a state-of-the-art hybrid Molecular Dynamics / force biased Monte Carlo simulation model, that allows us to simulate self-consistently all relevant processes at the atomic scale. Specifically, we plan (i) to optimize the existing simulation model in order to reduce the required computation time and extend the model to PECVD-growth; (ii) to perform specific simulations to simulate the growth of SWNTs under realistic (PECVD) process conditions on nickel nanocatalysts; (iii) to perform parameter studies that allow us to investigate the effect of the variation of precisely one parameter at a time, in order to determine how we can influence the growth process; and (iv) to develop a force field parametrization for Ni/Fe alloys to be used in the interatomic potential, and subsequent simulation of the PECVD-growth of SWNTs on Ni/Fe nanocatalysts. The innovative character of this project consists of (i) the use of the accurate interatomic potential in combination with the use of the hybrid MD/MC model that takes into account both short time scale as well as long time scale events; (ii) the study of SWNT growth in a PECVD-setup by means of atomistic simulations; and (iii) de development and application of Ni/Fe force field parameters for the simulation of PECVD-growth of SWNTs on Ni/Fe nanocatalysts. Although this project is indeed very innovative (both regarding the used methodology as the goals we are aiming for), we believe that this project is very feasible: indeed, we have already proven the effectivity of the simulation model in simulating the growth of SWNTs under thermal CVD conditions. Furthermore, we have access to all required tools needed to simulate the PECVD-specific process conditions. We therefore believe that we will be able to unravel fundamental processes in PECVD growth of SWNTs and to gain insight in this promising but until now at the atomic level nearly unexplored process." "Influence of clay tectonics in the North Sea on offshore wind foundation design and installation (Clay Tectonics)" "Marc De Batist" "Department of Geology" "The occurrence of Clay Tectonic Features (CTFs) in Paleogene clay layers in the Southern Bight of the North Sea was first reported in the 1980s (e.g. Henriet et al. 1983 and Henriet et al. 1988). These features include polygonal fault networks and other deformations such as diapiric structures. One of these clay layers is the Kortrijk Formation which is the main substrate for the installation of the planned offshore wind farms (OWF) in the Princess Elisabeth Zone in the Belgian part of the North Sea. Even though the presence of CTFs in this formation is well documented, the effect of these features on the stability and geotechnical properties of the clay, especially under significant external forcing (e.g. piling of a monopile), is unknown and requires in-depth study. Moreover, evidence exists that faults were reactivated after they were formed, underlining that these features may negatively affect the stability of the clay. Therefore, the Clay Tectonics project will apply an integrated geophysical / geological / geotechnical approach to investigate the occurrence and formation of clay tectonic deformation features in stiff clay layers, as well as their influence on offshore wind foundation design and installation.The following scientific objectives are envisaged:The development of an innovative field measurement and processing strategy to generate ultra-high resolution (pseudo) 3D seismic data volumes that adequately visualize the different types of CTFs occurring in the Kortrijk Formation. A thorough characterization of the CTFs in the selected study areas is foreseen, requiring that both large-scale elements (e.g. properties of the fault network as a whole) and small-scale elements (e.g. features related to individual faults) are well represented in the seismic data. In this regard, various acoustic techniques with different (high to ultra-high) resolution will be combined and a pipeline will be developed to optimally process and integrate the different datasets.A detailed geological analysis and reconstruction of the CTFs in the Kortrijk Formation to further elucidate their genesis and (potential) reactivation, as well as the underlying processes and parameters affecting the distribution, style and intensity of the deformations. This objective includes a careful mapping and characterization of the prevailing CTFs in the 3D seismic volume, an advanced statistical analysis of the variation in the prevailing seismic attributes of the deformation features, as well as a detailed investigation of reactivation features.The integration of geophysical and geotechnical parameters for a realistic geotechnical characterisation of the Kortrijk Clay Formation (ground model), to be used for numerical simulations in the context of offshore wind development. In order to reach this objective a dedicated onshore field sampling survey of fault sections in the Kortrijk Formation is foreseen, followed by a thorough mineralogical and geotechnical characterization of the sediment. Finally, a detailed comparison of a design or installation assessment with and without due consideration of the faults will be performed to quantify the foundation-related risks." "Adaptive Resolution Approach in Simulation of Complex Polymer Structures" "Giovanni Samaey" "Numerical Analysis and Applied Mathematics (NUMA), Polymer Chemistry and Materials" "The study of polymer-based composites is a challenging multiscale problem, involving multiple time and length scales. From specific interface interactions to macroscopically observable mechanical failure, the time and length scales range from femtosecond and sub-angstrom to years and metres, respectively. Computer simulations predicting the behaviour at the largest scales from the finest atomistic details remain impossible in the foreseeable future. Therefore, coarse-grained models are usually used, which approximate the material behaviour at the level of interest, but at the expense of losing information.However, to understand processing-structure-property relationships of the new materials, also atomistic/molecular structure information is required.This thesis tackles two of the main problems in the molecular simulation of polymeric materials: simulation of chemical reactions at the coarse-grained level and reverse mapping to the fine-grained level.The importance of simulating chemical reactions is especially visible in composite materials where the processes at the interface can influence the macroscopical properties.The reactive processes can already be simulated, in great details, using methods known from computational chemistry.However, the most significant drawback is the computational cost required to run the simulation.The classical molecular dynamics, using so-called non-reactive force-fields, proved its ability to predict properties of large systems at long timescales.For few decades, significant efforts have been put to incorporate chemical processes into the classical MD simulation, both into the fine-grained and the coarse-grained representations.The first part of this thesis is devoted to this effort.We propose a general method that allows simulating a step-growth polymerization process with the possibility of splitting the water molecules.Although the coarse-grained simulation can already predict certain properties of the simulated systems, still the fine-grained representation can be necessary to calculate specific properties such as permeability or the glass transition temperature.The second part of this work is devoted to a method that allows seamlessly transit from the coarse-grained to fine-grained representation.We proposed a generic reverse map approach that can be used for various polymeric systems, from simple polymer melts of linear chains to complex polymer networks.The solutions proposed in both of the parts are firmly influenced by the adaptive resolution approach, which was developed to simulate systems composed of two representations: a coarse-grained and a fine-grained." "New Water-Based Technology Platform for Future Non-Reactive Sealants" "Materials Chemistry" "Soudal is an international leader in sealants, adhesives and PU foams, continuously working on innovative solutions with a focus on more sustainable technologies. The general trend of high quality products with low ecological impact demands a responsible attitude towards the environment and use of resources. In this project, Soudal and UHasselt join forces to explore the potential of a water-based technology as a new high-quality and more sustainable solution for sealants. Although water-based sealants have been on the market for some time, there are some major drawbacks to this technology, e.g. shrinkage due to physical drying by the loss of water and lower elasticity and adhesion, limiting the use of this technology to lower demanding interior applications. Typical dispersion polymers used as binders in the water-based sealants are generally developed for other fields of application, such as paints/coatings or adhesives. Research into the synthesis of unique polymers and polymer properties could lead to the design of high performance water-based sealants that exceed the performance of standard water-based sealants on the market today. From this, we can start building a new platform to convert our sealants portfolio towards water-based user- and eco-friendly solutions that contribute to sustainability. This strengthens our position, and allows expansion of our production capacity to continue the current growth of 10 to 20% per year in the future"