Bart Partoens professor

Research Bart Partoens

Research team

Expertise

Characterization of structural, electronic, optical and magnetic properties of materials by means of first-principles (i.e. quantum-mechanical) electronic structure calculations. Characterization of the effect of defects and impurities in semiconductors and insulators.

Advancing photocatalytic water-splitting technology by reliable in silico design of the catalysts. 01/10/2022 - 17/11/2025

Abstract

Hydrogen is a renewable, high-energy-density and non-polluting energy carrier, hence its production and use are deservedly in prime attention of policy makers worldwide. In that respect, producing hydrogen using solar energy and photocatalytic water splitting presents both viable and environmentally friendly technology. However, progressing this technology to a widely applicable level requires an abundant yet highly efficient photocatalyst. Although many semiconducting materials have been proposed and synthesized for this purpose, some of them possess a relatively large bandgap with poor absorption for solar flux, while others suffer from the low photoexcited carrier rate, both of which severely decrease the photocatalytic performance. In addition, excitonic effects are usually neglected in the photocatalyst design, which leads to incorrect predictions of important properties such as optical absorption and band edge positions, ultimately yielding incorrect estimates of the key parameter - the solar-to-hydrogen (STH) efficiency. This project aims to radically change this unfavorable picture, and develop reliable predictive methodology to identify materials for photocatalytic water splitting with highest STH efficiency. The success of this project will not only advance the current modeling of photocatalysts, but will also provide cost-saving shortcuts to targeted experimentation towards viable technology for the use of water and light for hydrogen production.

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  • Research Project

Shapeable 2D magnetoelectronics by design (ShapeME). 01/01/2022 - 31/12/2025

Abstract

Novel materials that couple advanced magnetic and electronic properties are paramount to sustain the hunger of the modern society for advanced consumer electronics and Internet of Things, yet reduce the energy consumption and environmental impact. To satisfy the rather versatile needs of wearable, flexible, integrable, bio-compatible, ever smarter, and low power electronics, the paradigm shift is needed - towards tailored heterostructures, where different functionalities of the constituents are strongly coupled into a multifunctional hybrid. However, such strong interaction between different materials is challenging to realize, as much as their heterostructures are difficult to grow with sufficient control and quality. In this project, we will pursue the stacks of atomically-thin 2D materials as the most versatile yet fully controllable path towards shapeable magnetoelectronics by design. With properties broadly tunable by external mechanical, electric and magnetic stimuli, 2D materials are crystalline systems that nearly ideally connect the simulation environment to their practical behavior and measured quantities. To understand the deeply quantum phenomena behind the flexo-magnetoelectric coupling in 2D heterostructures, yet bridge them over to observables of practical value at micrometer scale, we formed a consortium of leading Belgian teams for suited multiscale simulations, the pioneer of 2D materials in UK for experimental validation, and imec as technology outlet.

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  • Research Project

Small-scale modeling of the dissolution behavior of platinum group metal nanoparticles in pyrometallurgical recycling from spent auto-catalysts. 01/11/2021 - 31/10/2025

Abstract

Platinum Group Metal (PGM) nanoparticles, more specifically platinum, rhodium, and palladium, are essential components in autocatalysts in the outlets of cars, since they work as active sites for catalytic reactions. Due to increasingly stringent environmental regulations, the demand for these metals increases yearly. Since PGMs are very scarce, efficient recycling of these metals has become an important issue. Currently, the smelting process is the most commonly employed pyrometallurgical approach for concentrating PGMs. The behavior of the PGM particles during the process cannot be observed directly in experiments, due to the scale of the industrial furnaces and the small size of the PGM nanoparticles. Computational modeling of this process can thus provide a very useful addition to fill this gap. This PhD aims to develop a modeling framework combining a multi-phase-field model with DFT calculations to study the local dissolution behavior of PGM nanoparticles from spent auto-catalysts in a metallurgical slag containing collector metal droplets. This framework will be used to uncover the dominant dissolution mechanism, leading to new insights into the effects of pyrometallurgical process parameters on the dissolution of these PGM particles, useful for interpreting observations from and optimizing industrial recovery operations. Once the framework is established, it could be applied to different recovery processes as well, increasing its relevance towards the industry.

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  • Research Project

Hybrid spin-charge quantum systems based of single point defects in diamond: Combined theoretical and experimental approach. 01/01/2021 - 31/12/2024

Abstract

Individual point defects in diamond crystals belong to an important class of quantum systems denoted as solid-state qubits. Such point defects, as for example NV, SiV, are intensively studied in the field of quantum sensing and metrology but also quantum information science. The applicants recently developed a novel technique, photoelectrically detected spin resonances in diamond, which brings promises for a new category of quantum devices that can be coupled with classical semiconducting electronics. The photoelectric readout is fundamentally based on charge state transitions in single point defects. In this respect, the photoelectric method differs from optical detection in two level quantum systems. In our proposal we would like to use this basic property of photoelectric readout and realise a novel type of qubit - charge-state solid qubit - using the transition between the different charge state of the same defect. Combining with the spin manipulations a hybrid quantum systems can be conceived. The proposal is based on preliminary results demonstrating the SiV charge state readout. To devise the mechanism of charge state transitions we will use predictive ab initio calculations theoretical methodology, permitting to determine the energy position of charge state levels in the diamond gap, photoionisation cross section, rates and the electron transport coherence with respect to the driving field. We will demonstrate charge-qubit superposition and two qubit entanglement.

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  • Research Project

Tunable opto-electronics in periodically strained two-dimensional materials. 01/11/2020 - 31/10/2024

Abstract

Periodic structures and flat bands realized experimentally in two-dimensional (2D) materials have recently proven to be a fertile ground for novel physics. I will take advantage of existing expertise and collaborations at CMT research group in order to propose periodically strained configurations of 2D materials, e.g. graphene, transition metal dichalcogenides or phosphorene, for the purpose of exploring novel opto-electronic phenomena related to (flat) electronic mini-bands or excitonic bands. To do so, I will first use numerical simulations to investigate how strong periodic strain modulations of several types can be engineered in 2D materials. Then, I will assess how these different types of modulations introduce band renormalization and how the latter, in its turn, affects optical and electronic properties of the 2D crystals in monolayer and multilayer form. In doing so, I will also be able to relate the role of external effects, such as applied electric fields, to the opto-electronic properties of these strained crystals. The external fields and periodic strains can function as a tuning knob for the opto-electronic response. Finally, I will investigate more deeply how periodic strain fields affect its excitonic properties. In this project, I will make use of the close collaborations of the CMT group with various experimental groups worldwide. The research is theoretical in nature, but I will repeatedly link my results to experiments to maximize impact of the research.

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Plasma for environmental, medical, analytical chemistry and materials applications. 01/05/2018 - 31/12/2024

Abstract

Plasma is an ionized gas. It is the fourth state of matter, next to solid, liquid and gaseous state. It exists in nature, but it can also be generated in laboratories by applying electric fields or heat to a gas. It consists of gas molecules, but also many reactive species, like electrons, various types of ions, radicals and excited species. This highly reactive chemical cocktail makes plasma interesting for many applications. We are studying the underlying mechanisms in plasma, including the plasma chemistry, plasma reactor design and plasma‐surface interactions, by means of computer simulations and experiments, to improve the following applications: (1) in materials science (for nanotechnology and microchip fabrication), (2) for analytical chemistry, (3) in environmental/energy applications (i.e., conversion of greenhouse gases and nitrogen fixation), and (4) for medicine (mainly cancer research).

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  • Research Project

Emerging phases of interlayer excitons in bilayers with flattened electronic bands. 01/10/2020 - 30/09/2023

Abstract

Recent experimental results on superconductivity in twisted bilayer graphene indicates that flat bands are a key feature to explore strongly correlated phases. A straightforward access to quasi-flat bands has also been realised by means of twisting or periodic straining in van der Waals heterobilayers made of transition metal dichalcogenides. By controlling the doping in bilayer systems, it is possible to generate interlayer excitons: electrons are confined in a layer and couples with holes, confined in the opposite and separated layer. In this project, I propose to theoretically study the effects of tunable flat bands on interlayer excitons with the aim to investigate the emergence of excitonic strongly correlated phases. At low temperature, a number of competing phases have been predicted, including electron-hole superfluidity, exciton insulator, coupled Wigner crystallisation and charged density waves. The enhancement of the effective masses of the carriers increases of the excitonic binding energy and this makes the excitonic phases more robust. By tuning the flatness of the bands it will become possible to enhance the critical temperature for electron-hole superfluidity and to control the emergence of the competing strongly correlated phases that appear in the phase diagram.

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Data fusion model for Cityflows. 01/10/2019 - 01/04/2023

Abstract

The University of Antwerp develops in this project in collaboration with IMEC a data fusion model for CityFlows, in which the density of motorized and non-motorized persons is obtained from the fusion of different data sources (including telco signalling data, Wifi scanning data, camera object detection, Telraam data, …).

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Personalization of the 3D audio experience 01/10/2019 - 30/09/2021

Abstract

3D-audio makes it appear as if sounds come from outside of your head, even better the sounds can come from everywhere: from above or below, from the front of the back. 3D-audio really immerses you into a soundscape: you become part of it, thereby improving the experience significantly. However, for the last couple of years the audio-visual sector has been struggling with a specific problem that stands in the way of the broad application of 3D-audio delivered through headphones: the sound processing involved has to be personalized. Recently, we developed at the UA a low-cost method to measure the Head-Related Transfer Function (HRTF) that allows such personalization. The main goal of this project is to turn the lab-version of this HRTF measurement method into a more robust and user-friendly method that can be applied outside the laboratory and for which we can prove the effectivity/usefulness to third parties using custom-built demonstrator applications. This will allow us to fulfill the prerequisites for commercializing our HRTF measurement technology through a spin-off.

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The information content of dynamic cues in human sound localization. 01/01/2019 - 31/12/2022

Abstract

Understanding the workings of human sound localization, and in particular which acoustic cues we use to perceive our acoustic environment in three dimensions (3D), is not only of fundamental interest, but has become increasingly relevant in the light of nowadays advance of 3D audio displays through headphones. In the past, most research has focused on the role of static cues , i.e. when the head and source are stationary, yet it is known that localization is greatly improved if listeners are allowed to move their head during stimulus presentation. In this project, we investigate the role of dynamic cues provided by small movements of the head or source, within an information- theoretic framework. We use a proven ideal-observer model for static human sound localization and extend it to account for the dynamic acoustic cues involved. First, we study what head movements carry the most information and how this depends on the location of the source. Next, we consider the mirror situation and investigate how much information can be conveyed through small movements of the source. Finally, we study the effects on sound localization when actual head movements are not taken into account correctly, which is the case if a 3D audio display is provided through ordinary headphones. The predictions from the theoretical analysis are validated with psycho-acoustic experiments.

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Transition metal dichalcogenides as unique 2D platform for collective quantum behavior. 01/10/2018 - 30/09/2021

Abstract

Two-dimensional transition metal dichalcogenides (2D-TMDs) are atomically-thin materials at the forefront of research, owing to their special electronic and optical properties, their tunability by electric gating and mechanical strain, and easy heterostructuring. It is much less explored that they also exhibit a wealth of collective quantum phases, characterized by a collective behavior of the electrons that is entirely different from their individual states. One such phase is a charge density wave, where electrons at lower temperatures form an ordered quantum fluid that restructures the host material. Another low-temperature collective quantum phase in 2D-TMDs is a superconducting one, where electrons condense into a resistance-less sea of Cooper pairs, that carries electric current without dissipation. Furthermore, the spins of the electrons add to the combinatorial possibilities for novel quantum states, and can form textures in monolayer TMDs that are wholly absent in the bulk. All these states are strongly intertwined, but the fundamentals of their interplay are not well understood – which hinders further progress towards novel functionalities and advanced applications. In this project, I will elucidate this interplay using state-of-the-art theoretical tools, and provide a roadmap to tailor it – by e.g. strain, gating and doping – in order to establish 2D-TMDs as a unique platform for highly versatile quantum devices, employing the advantages of all different states at play.

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3D audio personalization for virtual reality applications. 01/07/2018 - 30/06/2019

Abstract

Our previous research resulted in a low-cost and user-friendly do-it-yourself method that allows a user to measure their Head Related Transfer Function (HRTF) at home. While it is recognized that personalized 3D audio can add significant value to VR applications in a Business to Business environment, e.g. VR safety training, it appears that in addition to an efficient way of personalizing 3D audio, i.e. an HRTF measurement, two more elements are missing. First, the user having to assemble him/herself the measurement system from a number of commercially available components is perceived as a major obstacle. Second, the absence of standard software allowing effective use of personalized 3D audio acts as a significant impediment to its exploitation in applications. In this project we propose to remove these two obstacles to the use of personalized 3D audio in such Business to Business applications. The first obstacle will be addressed by developing a hardware module capable of capturing and transmitting both head movements and binaural microphone signals to a smartphone/laptop. In addition, we will extend Unity, a development platform widely used in the VR and game world, with a 3D audio module. This software module will allow application-developers to include personalized 3D audio in a standardized way in their products. Users of 2 these products can then upload their measured HRTF and experience the advantages of personalized 3D audio.

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The quest for the ground state of two-dimensional III-V semiconductors. 15/03/2017 - 14/03/2021

Abstract

The research on two-dimensional nanomaterials has grown exponentially after the experimental realization and characterization of graphene in 2005. Many new atom-thick material sheets have been theoretically proposed and experimentally realized since then and new possible structures are still predicted on a regular basis. To find new and possibly better materials for opto-electronics applications, it seems natural to investigate if 3D bulk materials that are already used for these applications can be scaled down to the 2D single layer limit, to even improve or tune their properties. This route has been followed for the group IV elements, leading to silicene, germanene, etc. Surprisingly, much less attention has been paid to the class of III-V materials, like InAs, GaAs, … Only the properties of these III-V compounds in the graphene-like (flat) or silicene-like structure (buckled) have thoroughly been investigated. However, it is well-known from molecular chemistry that group-III elements prefer planar sp2-bonded structures, as in trihydrides and trihalides, while group-V elements prefer tetragonal sp3-bonded configurations. It can be expected that these trends will pop-up again when reducing the 3D III-V bulk semiconductors to their 2D limit. The goal of this project is to identify the real ground state structures of 2D III-V compounds and to explore their electronic properties, using first-principles calculations. Another important field of research that arose from the research on graphene and graphene-like systems are topological insulators and the quantum spin Hall effect. The origin of this behavior lies in a band inversion, often realized by a strong spin-orbit coupling. So once we have determined the ground and metastable structures of the 2D compounds containing Tl and Bi, their topological character will be determined. The outstanding performance of many of today's opto-electronic devices is primarily due to the application of heterostructures, for example in lasers. Therefore it is also important to investigate the electronic properties of heterostructures composed of different 2D III-V semiconductors. Finally it is also natural to extend this research to the class of II-VI semiconductors.

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Low-cost head-related transfer function personalization to enable 3D audio for the masses. 01/01/2016 - 31/12/2017

Abstract

In this project we develop a new method for a person to individualize his/her head-related transfer function, a prerequisite for creating a realistic 3D audio environment through headphones. The method makes use of a smartphone and a few extra low-cost items, and can be carried out at home, by the user herself. The lack of experimental control is compensated for by complex post-processing of the measurement data. The method aims at opening up 3D audio technology for the masses.

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Electron microscopy for materials research (NANOcenter). 01/01/2015 - 31/12/2020

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

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Nano consortium of excellence. 01/01/2015 - 31/12/2019

Abstract

The NANO consortium of excellence represents the internationally renowned expertise in nanoscience at the University of Anwerp. It consists of three participating groups that are international leaders in their subfield: EMAT, CMT and PLASMANT. The consortium joins forces towards a uniform communication and collaboration in order to further strengthen the international position of the nanosciences at the University of Antwerp.

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SOLARPAINT: Understanding the durability of light sensitive materials: transferring insights between solar cell physics and the chemistry of paintings. 01/01/2015 - 31/12/2018

Abstract

When light interacts with matter, it responds to this external stimulus in ways that depend on macroscopic properties but also on the microscopic details of the material. Pigments for instance, have a wavelength dependent reflection and absorption that causes the appearance of color in e.g. oil paintings. The absorption of light can also be used to capture the energy stored in solar light for use in photovoltaic solar cells. Perhaps surprisingly, the microscopic function of solar cells and pigments have a lot in common. Both absorb light and suffer from deterioration upon prolonged illumination and environmental conditions. This leads to chemical degradation (and altered colors) in historical paintings and to gradually reducing efficiencies in organic solar cells. In order to better understand their function and alteration behaviour, in this project, we propose to study in detail the microscopic origins of the capturing of light in heterogeneous materials found in oil paints and organic solar cells by combining state of the art experimental techniques based on synchrotron radiation and electron microscopy with advanced quantum mechanical models. This multidisciplinary approach will enable to improve the function and durability of future organic solar cells and will help to preserve and restore historical paintings from our cultural heritage.

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Ab initio study of the band-lineup problem in twodimensional systems. 01/10/2014 - 30/09/2017

Abstract

In this project, we propose to investigate the electronic properties of two-dimensional (2D) heterostructures. Heterostructures can be defined as the combination of different materials into a single structure in which the various materials maintain their general characteristics. Another useful term is that of a heterojunction which can be regarded as the interface between two solid-state materials. Heterostructures are of both technological and fundamental interest. The technological importance is easily acknowledged in such fields as solid-state electronics and optoelectronics, but they are also of profound fundamental interest for materials science.

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Nanostructured topological insulators. 01/10/2014 - 30/09/2016

Abstract

The route we propose is by nanostructuring TIs. For example, in this project we study by ab initio density functional theory calculations thin slabs of TIs, and their interaction with normal insulating layers, and the effect of the adsorption of atoms on the surface of a TI on its surface electronic structure. Also the influence of magnetic impurities is of great importance, as they will destroy the topological surface states. Another class of nanostructured TIs are cylindrical nanowire TIs which are expected to show a rich surface electronic structure.

Researcher(s)

  • Promoter: Partoens Bart
  • Co-promoter: Sorée Bart
  • Fellow: De Beule Christophe

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Theoretical study of relativistic electron vortex waves. 01/10/2014 - 31/12/2015

Abstract

The goal of this FWO Aspirant proposal is to contribute to the theoretical and conceptual understanding of these newly created vortex beams and their interaction with matter. With this proposal we want to complement the experimental capabilities with a solid foundation of theoretical understanding in order to stay at the forefront of electron vortex research.

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Multiscale in Silico Study of Multiband Superconductors. 01/10/2014 - 30/09/2015

Abstract

One Fe-based superconductor that attracted a lot of attention recently is FeSe. The growing evidence suggests that monolayer FeSe superconducts up to 65 K and may become an ideal model system for testing several theoretical ideas [He13,Tan13]. Latter references show the importance of the substrate as a source of strain in the superconducting properties. Intriguingly, monolayer FeSe displays an important feature common to many superconductors: an inflection in the band structure (i.e. small or zero Fermi velocities) at energies that fall within the gap that opens below the critical temperature. This indicates again that a detailed knowledge of the electronic structure is a prerequisite for a successful theory

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Synthesis, properties and modeling of doped ZnO nanowires and nanocrystals. 01/01/2014 - 31/12/2017

Abstract

In this project, we will investigate the influence of different defects on the doping efficiency of ZnO nanowires (NWs) and nanocrystals (NCs), paying specific attention to the reliable p-type doping. On the other hand, we will explore the influence of the nanometer size dimensions on the electronic properties.

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Superconductivity per atomic layer. 01/01/2014 - 31/12/2017

Abstract

In this project, we will obtain theoretical insight in the effect of confinement and the choice of the substrate on the superconducting properties of atomistically thin films – by adding one monolayer at the time. Research will be performed via ab initio studies of the structural, electronic, and vibrational properties of few‐monolayer films, and the application of Bogoliubov‐de Gennes and Eliashberg formalisms to study the superconducting properties of these films, based on the input from the ab initio calculations.

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First-principles positron spectroscopy of topological insulators. 01/01/2014 - 31/12/2017

Abstract

In this project we will build on the well developed ab intio techniques for the study of positrons in bulk solids and on previous models to provide an ab initio theory of positron surfaces states. We will apply this theory to study the interaction of positrons with topological insulator surfaces.

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Mechanical properties and chemical bonding at the interfaces in polymer-based composite materials (InterPoCo). 01/03/2013 - 28/02/2017

Abstract

The main goals of the SB01 project "Mechanical properties and chemical bonding at the interfaces in polymer-based composite materiais" (InterPoCo) within the H-INT-S program are to (i) develop and apply a set of experimental and computational tools for comprehensive structural, compositional and quantitative mechanical characterisation of the interfaces in polymer-based composites at na no- and microscale level, (ii) to measure and predict structural, electronical, compositional, thermodynamica I and mechanical properties of bulk polymers and interfaces in polymer-based composites, (iii) to validate and improve the prediction reliability by emphasizing the interplay between modelling and experimental data obtained using a high-throughput approach and advanced characterisation results and (iv) to provide currently unavailable information on the above aspects to the running and future vertical SIBO programs.

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A quantum solver for junctionless III-V quantum devices. 01/10/2012 - 30/09/2016

Abstract

The aim of the PhD is to construct a quantum solver for investigating transport in highmobility two(three)-dimensional electron gases residing in the active areas of junctionless III-V structures and devices. A substantial effort will go into the numerical implementation of the quantum transport equation - e.g. the Wigner-Liouville equation - describing the steering quantum effects in the transport direction, the Schrödinger equation accounting for lateral quantum confinement, Poisson's equation fixing the local electrostatic potential and the constitutive equations yielding the densities and invoking a fully self-consistent coupling between all equations.

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Theoretical study of relativistic electron vortex waves. 01/10/2012 - 30/09/2014

Abstract

The goal of this FWO Aspirant proposal is to contribute to the theoretical and conceptual understanding of these newly created vortex beams and their interaction with matter. With this proposal we want to complement the experimental capabilities with a solid foundation of theoretical understanding in order to stay at the forefront of electron vortex research.

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Ab initio study of nanostructured topological insulators. 01/10/2012 - 30/09/2014

Abstract

The route we propose is by nanostructuring TIs. For example, in this project we study by ab initio density functional theory calculations thin slabs of TIs, and their interaction with normal insulating layers, and the effect of the adsorption of atoms on the surface of a TI on its surface electronic structure. Also the influence of magnetic impurities is of great importance, as they will destroy the topological surface states. Another class of nanostructured TIs are cylindrical nanowire TIs which are expected to show a rich surface electronic structure.

Researcher(s)

  • Promoter: Partoens Bart
  • Co-promoter: Sorée Bart
  • Fellow: De Beule Christophe

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  • Research Project

Junctionless III-V quantum devices new concepts and transport properties. 01/07/2012 - 30/06/2016

Abstract

The aim of the project is to investigate quantitatively the potential and perspective of a class of newly proposed semiconductor device concepts based on the geometry and architecture of the junctionless IlI-V nanowire transistor. Moreover, a common feature to be shared by all concepts is the requirement that quantum mechanics be a crucial part of the working principle that governs the active device areas.

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Electronic structure of modified graphene. 01/10/2011 - 30/09/2014

Abstract

The project deals with the theoretical characterization of functionalized graphene. Graphene is a recently (2004) discovered material with extraordinary electronic and mechanical properties. For some applications of graphene in nanothechnology it is important to change its properties. E.g. there is a problem for using graphene as the channel material in transistors because the conductivity of graphene always remains finite, i.e. the transistor can not be switched off. This problem can be overcome by functionalizing graphene, i.e. by the chemical attachment of atoms and molecules on a graphene surface. But functionalization is also important for other applications in e.g. biotechnology and spintronics. In this project I plan to investigate this functionalization by simulating it on an atomic level with theoretical models and examining the resulting changes in the electronic and mechanical properties.

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Electronic and structural properties of complex oxide multilayer systems at the atomic scale: a (S)TEM and EELS investigation. 01/10/2011 - 30/06/2012

Abstract

During this project novel oxide materials (layered systems) will be characterized to provide insight in their macroscopic properties. The techniques used, (scanning) transmission electron microscopy (S/TEM) and electron energy loss spectroscopy (EELS), will provide chemical and structural information down to the atomic scale due to the improved resolution of the QU-Ant-EM microscope. Several data analysis techniques will be compared and adapted in order to maximize the output of information obtained in these experiments.

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Optimization of the structure-activity relation in nanoporous materials. 01/01/2011 - 31/12/2014

Abstract

The relation between structure and activity will be optimized for two classes of nanoporous materials: TiO2 nanotubes combined with Ag nanoparticles and Periodic Mesoporous Organosilica's. This will be done based on a multidisciplinary approach combining advanced 3-dimensional imaging with modern computational methods at an atomic scale. This will lead to a more direct optimization of the synthesis and activity of the nanoporous materials in comparison to the classic trial-and-error procedures.

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Irreversibility and efficiency in small-scale systems. 01/01/2011 - 31/12/2014

Abstract

In contrast to the basic microscopic laws in physics, which are symmetric on time reversal, most macrocopic phenomena are characterized by irreversible behavior. Recently exact expressions for the entropy production and thermodynamical efficiency were proposed. Within this project we want to investigate how these results can be applied to small-scale systems like two-dimensional quantum dots, classical Coulomb clusters, photoelectric and electro-chemical devices. The main goal of this project is to propose experimental systems and to determine with computer simulations the conditions under which the effects of irreversibility and efficiency in small-scale systems can be observed experimentally.

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Electronic structure of patterned graphene. 01/10/2010 - 30/09/2014

Abstract

Many of the fascinating properties of graphene follow from its gapless linear spectrum. However, most electronic applications rely on the presence of a gap. In this project we investigate by ab initio calculations how different ways of patterning graphene can be used to realize a band gap in graphene. We focus on graphene patterned into graphene/graphane nanoribbons, graphene patterned by hydrogen adsorption and by defects, and hybrid graphene structures.

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SILASOL - New Silicon Materials for Solar Applications. 01/01/2010 - 31/12/2013

Abstract

Silicon solar cells are the work horse of the photovoltaic energy conversion from sunlight into electricity.The SILASOL project focuses on new silicon-based materials for PV applications: by changing the shape of the silicon material (thinner wafers, nanowires, ...), or the synthesis method (CVD, mechanical cleavage, ...), the "new" Si material acquires specific properties (bandgap, crystallinity, ...) that can be used advantageously for PV applications. The technology development is in Imec (Leuven), the task of the UA is the experimental and computational characterization of these advanced silicon nanostructures.

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Nanostructured and nonhomogeneous quantum wires. 01/01/2009 - 31/12/2012

Abstract

The objective of this project is the theoretical study of the electronic properties of: - Lateral and radial nanostructured quantum wires. We will investigate the optical and transport properties. - Nonhomogeneous quantum wires. Study of effects due to geometrical fluctuations (i.e. lateral variations in the radius), of disorder, and of scattering on impurities and phonons on the electronic transport.

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In Silico Materials Design and experimental validation for novel optical coatings (ISIMADE). 01/01/2009 - 31/12/2012

Abstract

The primary objective of this SBO is to develop advanced tools for pragmatic materials modeling. However, to stimulate the interaction with experimental work at Flamac and their industrial partners early on, we have targeted one application area; particularly optical thin film materials. These applications have been chosen on the basis of their high technological relevance, industrial interest in Flanders, environmental issues, and feasibility to make impact with modeling.

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Ab initio calculations of semiconductor nanowires. 01/10/2008 - 30/09/2010

Abstract

In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

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Iterative methods for linear and non-linear Schrodinger equations 01/01/2008 - 31/12/2011

Abstract

The aim of the project is to develop efficient computational methods, based on Krylov space methods, to solve the linear and non-linear Schrödinger equations. This will enable the theoretical methods to move from the approximate 2D models to the more realistic 3D description. The methods will be applied to practical physical problems: to solve the non-linear time-dependent and time-independent Ginzburg-Landau equations for the study of the vortex structure and dynamics in mesoscopic superconductors and to solve the linear Schrödinger equation for realistic self-assembled quantum dots.

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Electronic and optical properties of transparent conducting oxides: an ab initio study. 01/01/2008 - 31/12/2011

Abstract

Within this project we will study in a systematic way the relation between composition and structure versus the electronic and optical properties of transparent conducting oxides (TCO) by means of ab initio electronic structure calculations.

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Structural and electronic properties of biologically modified graphene-based layers. 01/01/2007 - 31/12/2010

Abstract

Aims of the research project: (i) to optimize the preparation and patterning of graphene-based layers to which biomolecules are attachted and (ii) to understand the magnetotransport properties of such layers in a wide temperature range before and after attaching the biomolecules. The results of these investigations will be applied to develop a sensitive electronic monitoring of specific biological processes in a liquid environment, including the denaturation and rehybridization of DNA molecules, and the sensing of immunoglobulin and immunoglobulin-antigen binding.

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Modelling of nanostructures and classical clusters. 01/10/2006 - 30/09/2008

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Ab initio calculations of semiconductor nanocrystals: wires and clusters. 01/10/2006 - 30/09/2008

Abstract

In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

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High-precision reliable floating-point arithmetic and nanotechnology. 01/01/2006 - 31/12/2009

Abstract

Virtually all present-day computer systems, from personal computers to the largest supercomputers, implement the IEEE 54-bit floating-point arithmetic standard, which provides 53 binary or approximately 15 decimal digits accuracy. For most scientific applications, this is more than sufficient. However, for a rapidly expanding body of applications, 54-bit IEEE arithmetic is no longer sufficient. These range from some interesting new mathematical investigations to large-scale physical simulations performed on highly parallel supercomputers. Moreover in these applications, portions of the code typically involve numerically sensitive calculations, which produce results of questionable accuracy using conventional arithmetic [3]. These inaccurate results may in turn induce other errors, such as taking the wrong path in a conditional branch. Such blocks of code benefit enormously from a combination of reliable numeric techniques and the use of high-precision arithmetic. Indeed, the aim of reliable numeric techniques is to deliver, together with the computed result, a guaranteed upper bound on the total error or, equivalently, to compute an enclosure for the exact result. It is perhaps not a coincidence that interest in high-precision computations has arisen in the same period that many scientific computations are implemented on highly parallel and distributed, often heterogeneous, computer systems. Such systems have made possible much larger-scale runs than before, greatly magnifying numerical difficulties. Switching from hardware to high-precision arithmetic to tackle these difficulties, has benefits in its own right. Since high-precision arithmetic is implemented in software, the result is independent of the specific hardware in the heterogeneous system on which it is computed. In [3] the successful solution of several problems in scientific computing using high-precision arithmetic is described. It is worth noting that all of these successful applications of high-precision arithmetic have arisen in the past ten years. This may be indicative of the birth of a new era of scientific computing, in which the numerical precision required for a computation is as important to the program design as are the algorithms and data structures. Aim of the project It is the aim of the project team to contribute to the solution of a number of open problems in computational physics, in particular nanotechnology, which require the use of high-precision and reliable computations. The nanoscopic domain is a scale of length situated between the microscopic (atom and molecular scale) and the macroscopic scale. Characteristic for nanotechnology research is that a finite number (on the order of 10 to 10000) of particles (e.g. atoms, molecules, electrons) are involved, and hence that surface effects are of crucial importance. The large number of particles implies that it is practically impossible to obtain analytic results and that one needs to focus on computational methods. As will become clear from the project description, the key to the solution of the open problems in nanotechnology is the high-precision, reliable evaluation of certain special functions. Up to this date, even environments such as Maple, Mathematica, MATLAB and libraries such as IMSL, CERN and NAG offer no routines for the reliable evaluation of special functions.

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    Nanowires: optical and transport properties. 01/10/2005 - 30/09/2006

    Abstract

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    Ab initio calculations of semiconductor nanocrystals: wires and clusters. 01/10/2005 - 30/09/2006

    Abstract

    In this project we will perform ab initio total-energy calculations within the pseudopotential density-functional theory (DFT) on experimentally realized nanoclusters and nanowires. This approach allows us to study, on an atomic scale, the structure and electronic properties of these semiconducting nanocrystals.

    Researcher(s)

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    • Research Project

    Ab initio calculations of semiconductor nanowires. 01/05/2005 - 30/04/2009

    Abstract

    Ab initio total energy calculations will be performed in the pseudopotential density functional theory formalism for the recently experimentally realised freestanding Si, Ge, ZnO, ... nanowires. This approach allows to study the atomistic and electronic structure of the nanowires. Also the influence of external molecules (like charge transfer) will be studied, to gain insight in the functioning of such wires as nanosensors.

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    Ab initio calculations of semiconductor nanocrystals. 01/05/2005 - 31/12/2006

    Abstract

    Ab initio total energy calculations will be performed in the pseudopotential density functional theory formalism for the recently experimentally realised freestanding semiconductor nanowires and nanoclusters. This approach allows to study the atomistic and electronic structure of the nanowires and nanoclusters. Also the influence of external molecules (like charge transfer) will be studied, to gain insight in the functioning of such wires as nanosensors.

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    Electronic properties of semiconductor quantum wires and quantum rings. 01/01/2005 - 31/12/2008

    Abstract

    The objective of this project is the theoretical study of the electronic properties of quantum wires and quantum rings.

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    Electron correlations in nanostructures : classical and quantum systems. 01/10/2003 - 30/09/2006

    Abstract

    In this project we study the effects of electron correlations in quantum mechanical as well as classical systems. In the quantum mechanical part of this project, the current research in the electronic properties of quantum dots and coupled quantum dots will be continued and extended to multi-excitons and wires. In the classical part we study dynamical properties of classical clusters using molecular dyunamics simulation techniques.

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    Structure and dynamics of vortices and charged particles in mesoscopic confined systems. 01/01/2002 - 31/12/2007

    Abstract

    Theoretical study of thermodynamic properties and time dependent phenomena in confined mesoscopic systems. Investigation of the driving forces behind ordering. The aim is to find the underlying principles governing order and melting in different two-dimensional experimental realizable systems.

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    Correlations on bio-surfaces. 01/09/2001 - 31/08/2003

    Abstract

    The importance of correlations, for example between water molecules, on bio-surfaces will be investigated theoretically. First we will study the geometrical structure of the water molecules that are hydrogen bonded to the protein surface and its effect on the transport of motor proteins. Next we will investigate the charge inversion of proteins, which is a consequence of correlations between ions bonded to the protein surface.

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      Theoretical study of electon correlation in classical and quantum dots in strong magnetic fields. 01/10/2000 - 30/09/2003

      Abstract

      Electron correlation in quantum dots and in coupled quantum dots will be studied in the presence of an external magnetic field. The dynamics of the Wigner crystal will be studied. Quantum dots in the fractional quantum Hall regime will be studied and the interplay of this state with the Wigner solid will be investigated. Excitons in such quantum dots will also be studied.

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        Artificial atoms : structure and energy relaxation. 01/10/1998 - 30/09/2000

        Abstract

        Theoretical study of the properties of artificial atoms in semiconductor nanostructures. Investigations of the correlations between the electrons and their energy relaxation.

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          Artificial atoms : structure and energy relaxation. 01/10/1996 - 30/09/1998

          Abstract

          Theoretical study of the properties of artificial atoms in semiconductor nanostructures. Investigations of the correlations between the electrons and their energy relaxation.

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            • Research Project