ERC FUNDED PROJECTS

The standard variational principles (VPs) are cornerstones of quantum mechanics, and one can hardly overestimate their usefulness as tools for generating approximations to the time-independent and time-dependent Schröodinger equations. The aim of the proposal is to study and apply a generalization of these, the bivariational principles (BIVPs), which arise naturally when one does not assume a priori that the system Hamiltonian is Hermitian. This unconventional approach may have transformative impact on development of ab initio methodology, both for electronic structure and dynamics. The first objective is to establish the mathematical foundation for the BIVPs. This opens up a whole new axis of method development for ab initio approaches. For instance, it is a largely ignored fact that the popular traditional coupled cluster (TCC) method can be neatly formulated with the BIVPs, and TCC is both polynomially scaling with the number of electrons and size-consistent. No “variational” method enjoys these properties simultaneously, indeed this seems to be incompatible with the standard VPs. Armed with the BIVPs, the project aims to develop new and understand existing ab initio methods. The second objective is thus a systematic multireference coupled cluster theory (MRCC) based on the BIVPs. This is in itself a novel approach that carries large potential benefits and impact. The third and last objective is an implementation of a new coupled-cluster type method where the orbitals are bivariational parameters. This gives a size-consistent hierarchy of approximations to multiconfiguration Hartree--Fock. The PI's broad contact with and background in scientific disciplines such as applied mathematics and nuclear physics in addition to quantum chemistry increases the feasibility of the project.

1 499 572 €

Start date: 2015-04-01, End date: 2020-03-31

The field of electronics has been a veritable powerhouse of the economy, driving technological breakthroughs that affect all aspects of everyday life. Aside from silicon, there has been growing interest in developing a novel generation of electronic devices based on pi-conjugated polymers and oligomers. While their goal is not to exceed the performance of silicon technologies, they could enable far reduced fabrication costs as well as completely new functionalities (e.g. mechanical flexibility, transparency, impact resistance). The performance of these organic devices is greatly dependent on the organization and electronic structures of π-conjugated polymer chains at the molecular level. To achieve full potential, technological developments require fine-tuning of the relative orientation/position of the pi-conjugated moieties, which provide a practical means to enhance electronic properties. The discovery pace of novel materials can be accelerated considerably by the development of efficient computational schemes. This requires an integrated approach, based on which the structural, electronic, and charge transport properties of novel molecular candidates are evaluated computationally and predictions benchmarked by proof of principle experiments. This research program aims at developing a threefold computational screening strategy enabling the design of an emerging class of molecular precursors based on the insertion of π-conjugated molecules into self-assembled hydrogen bond aggregator segments (e.g. oligopeptide, nucleotide and carbohydrate motifs). These bioinspired functionalized pi-conjugated systems offer the highly desirable prospect of achieving ordered suprastructures abundant in nature with the enhanced functionalities only observed in synthetic polymers. A more holistic objective is to definitively establish the relationship between highly ordered architectures and the nature of the electronic interactions and charge transfer properties in the assemblies.

1 482 240 €

Start date: 2012-12-01, End date: 2017-11-30

Proteins perform their biological function following specific sequences of events. During these dynamical paths, highly non-trivial cooperative interactions occur. Ultimately, this is the origin of the emerging collective behavior that makes proteins the most sophisticated existing molecular machines. This complex network of processes covers a wide range of timescales, from few fs to ms, and distances, from atoms to large protein domains. Even the most recent experimental techniques generally provide ns-to-us averaged structural and dynamical information, often in non-physiological conditions. To access simultaneously atomic time and length scales would unveil the elementary conformational steps constituting a functional event and their temporal evolution. I propose to extend emerging multidimensional ultrafast optical spectroscopic techniques to the deep ultraviolet. These techniques are the analogue of multidimensional Nuclear Magnetic Resonance methods and are able to provide structural information exploiting electric dipole couplings but with fs temporal resolution. The novel extension to ultraviolet, that I shall implement, will open the possibility to exploit the optical absorption of aromatic amino-acid residues with the great advantage of studying wild type proteins. In this way, all drawbacks due to artificial labeling will be ruled out. I will use this new technique to study dynamic-assisted long range electron transfer in copper proteins and enzyme regulation in hemoglobin. These two proteins of great importance from a biological point of view have been chosen because their functions are a clear manifestation of cooperative phenomena. On a long term prospective this methodology will be a universal tool applicable to any wild type protein containing aromatic amino acids.

1 473 600 €

Start date: 2012-01-01, End date: 2016-12-31

In a truly cross-disciplinary research project encompassing surface science, astrophysics and chemistry we aim to address two of the major outstanding questions in the field of astrochemistry, namely i) how molecular hydrogen, the most abundant molecule in the interstellar medium, form, and ii) whether it is possible to identify specific Polycyclic Aromatic Hydrocarbon (PAH) species in interstellar spectra. The insights gained from the experimental investigations may revolutionize our current understanding of astrochemistry and will have impact even beyond the field. Special emphasis will be placed on the impact our findings will have on ascertaining the suitability of PAHs as a hydrogen storage medium. By combining scanning tunneling microscopy, thermal desorption spectroscopy, laser-induced thermal desorption time-of-flight mass spectrometry, fluorescence spectroscopy experiments and density functional theory calculations we will map out the interaction of atomic hydrogen with PAHs. The goal of the investigation is to obtain atomic level understanding of the atomic hydrogen – PAH interaction in order to i) ascertain whether interstellar molecular hydrogen formation, contrary to present belief but in accordance with our recent calculations, could occur predominantly via interaction with PAHs, ii) measure the adsorption/emission spectrum of Hydrogen-PAH complexes and thereby facilitate observational detection of these complexes in the interstellar medium, iii) determine whether PAHs are a promising medium for hydrogen storage and iv) ascertain whether the hydrogen storage properties of PAHs are tunable by electro-magnetic radiation. This ambitious and cross-disciplinary research project will predominantly take place at the newly established Surface Dynamics Laboratory at the University of Aarhus, headed by the applicant, but will also benefit from fruitful collaborations already initiated with local, national and international colleagues.

1 499 810 €

Start date: 2008-07-01, End date: 2013-06-30

Emulsions consist of one liquid dispersed as nanoscopic droplets in another liquid, such as milk, and butter. The understanding of the structure and stability of emulsions is commonly obtained from empirical studies in which a macroscopic parameter (like temperature or concentration of constituents) is varied. Since the work of Irving Langmuir and others (published in 1917) it is well established that the stability and properties of these nanoscopic droplets are strongly influenced by the state of the droplet interface. However, despite the abundance and importance of emulsions in our daily lives, the molecular mechanisms that dictate the stability and properties of emulsions are still unknown. This lack of insight is caused by the system itself: the condensed surrounding medium forms an impenetrable barrier to most molecular probes. Nonlinear light scattering spectroscopy, a novel method I have developed (both theoretically and experimentally), offers a way of obtaining molecular information (chemical composition, molecular orientation, ordering and chirality) of the interfaces of nanoscopic particles in solution. With this method it should be possible to observe, in-situ, non-invasively and label-free, the molecules at the interface of the nanoscopic droplets in solution. I therefore propose to form a small group that investigates interfaces of nanoscopic droplets in emulsions on the molecular level and timescale. Using femtosecond nonlinear light scattering methods we can finally observe the molecules that dictate the structure and stability of emulsions in action.

1 150 000 €

Start date: 2009-11-01, End date: 2014-10-31

The research theme concerns the application of new experimental methods for atomic-scale characterization of model catalysts based on insulating metal oxides with the goal of exploring the potential for designing new and efficient heterogeneous catalysts by enhanced control of the catalyst structure at the atomic level. This objective will be achieved by a carefully integrated sequence of synthesis, characterization, and reactivity measurements of model catalysts based on insulating metal oxides. The project aims in detail at resolving some pertinent support synergies and size-effects, which have been revealed in catalytic systems. A core challenge and advance, which sets the project apart from previous research, is the application of high-resolution non contact Atomic Force Microscopy (nc-AFM), which is the only available tool that can resolve the atomic structure of insulator surfaces and the morphology of supported nanoclusters. I will combine my proven experience with atom-resolved imaging using nc-AFM with novel methods for synthesizing and analyzing model catalysts, to provide groundbreaking new atomistic insight. A crucial aspect will be the ability to relate nc-AFM observations to actual catalytic properties, and this will be achieved by using complementary surface spectroscopies and reaction measurements performed at real high pressure conditions. I firmly believe that this research strategy can provide the key insight to a significantly better understanding of the numerous catalytic systems based on insulating metal oxides, and this project will enable me to set up a unique world-class experimental facility for such studies.

1 050 000 €

Start date: 2009-10-01, End date: 2014-09-30

Immune cells constantly receive signalling inputs such as pathogen-emitted molecules, use gene regulatory pathways to process these signals, and generate outputs by secreting signalling molecules like cytokines. Characterizing the input-output relationship of a biological system helps understanding its regulatory mechanisms, and allows building models to predict how the system will operate in complex physiological scenarios, such as population tissue response to infection. A major obstacle in this endeavor has been the so-called “biological noise”, or significant variability in measured molecular parameters between cells. Such variability makes time-dependent single-cell analysis crucial to understand how biological systems operate. Development of new analytical tools with improved functionality, accuracy, and throughput is needed to realize the full potential of single-cell analysis. We propose to develop automated, high-throughput, Optofluidic single-cell analysis systems with unprecedented capabilities, and to use them in understanding how immune cells organize in tissue during response to infection. Microfluidic membrane-valves, nanodroplets, optics, and automation will be integrated to achieve an unparalleled degree of control over single immune cells. Multi-functional lab-on-chip devices will simultaneously measure: a) The activity of immune regulatory proteins such as NF-κB, and b) Inflammatory cytokines secreted from single immune cells in a time-dependent manner, under precisely defined biochemical inputs. Characterizing macrophage cytokine secretion dynamics under combinatorial regiments of bacterial and apoptotic-cell signals will allow dissecting the signalling mechanism responsible from the resolution of inflammation. We will identify the role of the NF-κB pathway in regulation of cytokine dynamics. We will use our data to develop a computer model of tissue-level immune response to pathogens through the NF-κB pathway and cytokine signaling.

1 499 165 €

Start date: 2013-10-01, End date: 2018-09-30

The project will develop new methods for calculating nonlinear spectroscopic properties, both in the electronic as well as in the vibrational domain. The methods will be used to study molecular interactions at interfaces, allowing for a direct comparison of experimental observations with theoretical calculations. In order to explore different ways of modeling surface and interface interactions, we will develop three different ab initio methods for calculating these nonlinear molecular properties: 1) Multiscale methods, in which the interface region is partitioned into three different layers. The part involving interface-absorbed molecules will be described by quantum-chemical methods, the closest surrounding part of the system where specific interactions are important will be described by classical, polarizable force fields, and the long-range electrostatic interactions will be described by a polarizable continuum. 2) Periodic-boundary conditions: We will extend a response theory framework recently developed in our group to describe periodic systems using Gaussian basis sets. This will be achieved by deriving the necessary formulas, and interface our response framework to existing periodic-boundary codes. 3) Time-domain methods: Starting from the equation of motion for the reduced single-electron density matrix, we will propagate the electron density and the classical nuclei in time in order to model time-resolved vibrational spectroscopies. The novelty of the project is in its focus on nonlinear molecular properties, both electronic and vibrational, and the development of computational models for surfaces and interfaces that may help rationalize experimental observations of interface phenomena and molecular adsorption at interfaces. In the application of the methods developed, particular attention will be given to nonlinear electronic and vibrational spectroscopies that selectively probe surfaces and interfaces in a non-invasive manner, such as SFG.

1 498 500 €

Start date: 2011-09-01, End date: 2016-08-31