ERC FUNDED PROJECTS

Polar materials, such as piezoelectrics and ferroelectrics are essential to our modern life, yet they are mostly developed by trial-and-error. Their properties overwhelmingly depend on the defects within them, the majority of which are hidden in the bulk. The road to better materials is via mapping these defects, but our best tool for it – piezoresponse force microscopy (PFM) – is limited to surfaces. 3D-PXM aims to revolutionize our understanding by measuring the local structure-property correlations around individual defects buried deep in the bulk. This is a completely new kind of microscopy enabling 3D maps of local strain and polarization (i.e. piezoresponse) with 10 nm resolution in mm-sized samples. It is novel, multi-scale and fast enough to capture defect dynamics in real time. Uniquely, it is a full-field method that uses a synthetic-aperture approach to improve both resolution and recover the image phase. This phase is then quantitatively correlated to local polarization and strain via a forward model. 3D-PXM combines advances in X-Ray optics, phase recovery and data analysis to create something transformative. In principle, it can achieve spatial resolution comparable to the best coherent X-Ray microscopy methods while being faster, used on larger samples, and without risk of radiation damage. For the first time, this opens the door to solving how defects influence bulk properties under real-life conditions. 3D-PXM focuses on three types of defects prevalent in polar materials: grain boundaries, dislocations and polar nanoregions. Individually they address major gaps in the state-of-the-art, while together making great strides towards fully understanding defects. This understanding is expected to inform a new generation of multi-scale models that can account for a material’s full heterogeneity. These models are the first step towards abandoning our tradition of trial-and-error, and with this comes the potential for a new era of polar materials.

1 496 941 €

Start date: 2019-01-01, End date: 2023-12-31

The description of high pressure phases or polymorphism of molecular solids represents a significant scientific challenge both for experiment and theory. Theoretical methods that are currently used struggle to describe the tiny energy differences between different phases. It is the aim of this project to develop a scheme that would allow accurate and reliable predictions of the binding energies of molecular solids and of the energy differences between different phases. To reach the required accuracy, we will combine the coupled cluster approach, widely used for reference quality calculations for molecules, with the random phase approximation (RPA) within periodic boundary conditions. As I have recently shown, RPA-based approaches are already some of the most accurate and practically usable methods for the description of extended systems. However, reliability is not only a question of accuracy. Reliable data need to be precise, that is, converged with the numerical parameters so that they are reproducible by other researchers. Reproducibility is already a growing concern in the field. It is likely to become a considerable issue for highly accurate methods as the calculated energies have a stronger dependence on the simulation parameters such as the basis set size. Two main approaches will be explored to assure precision. First, we will develop the so-called asymptotic correction scheme to speed-up the convergence of the correlation energies with the basis set size. Second, we will directly compare the lattice energies from periodic and finite cluster based calculations. Both should yield identical answers, but if and how the agreement can be reached for general system is currently far from being understood for methods such as coupled cluster. Reliable data will allow us to answer some of the open questions regarding the stability of polymorphs and high pressure phases, such as the possibility of existence of high pressure ionic phases of water and ammonia.

924 375 €

Start date: 2018-01-01, End date: 2022-12-31

We propose focused theory developments and applications, which aim to substantially advance our ability to model and understand the behavior of molecules in complex environments. From a large repertoire of possible environments, we have chosen to concentrate on experimentally-relevant situations, including molecular fluctuations in electric and optical fields, disordered molecular crystals, solvated (bio)molecules, and molecular interactions at/through low-dimensional nanostructures. A challenging aspect of modeling such realistic environments is that both molecular electronic and nuclear fluctuations have to be treated efficiently at a robust quantum-mechanical level of theory for systems with 1000s of atoms. In contrast, the current state of the art in the modeling of complex molecular systems typically consists of Newtonian molecular dynamics employing classical force fields. We will develop radically new approaches for electronic and nuclear fluctuations that unify concepts and merge techniques from quantum-mechanical many-body Hamiltonians, statistical mechanics, density-functional theory, and machine learning. Our developments will be benchmarked using experimental measurements with terahertz (THz) spectroscopy, atomic-force and scanning tunneling microscopy (AFM/STM), time-of-flight (TOF) measurements, and molecular interferometry. Our final goal is to bridge the accuracy of quantum mechanics with the efficiency of force fields, enabling large-scale predictive quantum molecular dynamics simulations for complex systems containing 1000s of atoms, and leading to novel conceptual insights into quantum-mechanical fluctuations in large molecular systems. The project goes well beyond the presently possible applications and once successful will pave the road towards having a suite of first-principles-based modeling tools for a wide range of realistic materials, such as biomolecules, nanostructures, disordered solids, and organic/inorganic interfaces.

1 811 650 €

Start date: 2017-03-01, End date: 2022-02-28

Cancer and other diseases are driven by genomic alterations initiated by DNA breaks. Within our genomes, some regions are particularly prone to breakage, and these are known as common fragile sites (CFSs). CFSs are present in every person and are frequently sites of oncogenic chromosomal rearrangements. Intriguingly, despite their fragility, many CFSs are well conserved through evolution, suggesting that these regions have important physiological functions that remain elusive. My previous background in genome editing, proteomics and replication-born DNA damage has given me the tools to propose an ambitious and comprehensive plan that tackles fundamental questions on the biology of CFSs. First, we will perform a systematic analysis of the function of CFSs. Most of the CFSs contain very large genes, which has made technically difficult to dissect whether the CFS role is due to the locus itself or to the encoded gene product. However, the emergence of the CRISPR/Cas9 technology now enables the study of CFSs on a more systematic basis. We will pioneer the engineering of mammalian models harbouring large deletions at CFS loci to investigate their physiological functions at the cellular and organism levels. For those CFSs that contain genes, the cDNAs will be re-introduced at a distal locus. Using this strategy, we will be able to achieve the first comprehensive characterization of CFS roles. Second, we will develop novel targeted approaches to interrogate the chromatin-bound proteome of CFSs and its dynamics during DNA replication. Finally, and given that CFS fragility is influenced both by cell cycle checkpoints and dNTP availability, we will use mouse models to study the impact of ATR/CHK1 pathway and dNTP levels on CFS instability and cancer. Taken together, I propose an ambitious, yet feasible, project to functionally annotate and characterise these poorly understood regions of the human genome, with important potential implications for improving human health.

1 499 711 €

Start date: 2016-05-01, End date: 2021-04-30