Objective 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. Fields of science natural sciencesphysical sciencesquantum physicsnatural scienceschemical sciencesphysical chemistryquantum chemistrynatural sciencesphysical sciencesclassical mechanicsstatistical mechanicsnatural sciencescomputer and information sciencesartificial intelligencemachine learningnatural sciencesphysical sciencesopticsmicroscopyscanning tunneling microscopy Keywords quantum fluctuations molecular environments complex systems Programme(s) H2020-EU.1.1. - EXCELLENT SCIENCE - European Research Council (ERC) Main Programme Topic(s) ERC-2016-COG - ERC Consolidator Grant Call for proposal ERC-2016-COG See other projects for this call Funding Scheme ERC-COG - Consolidator Grant Host institution UNIVERSITE DU LUXEMBOURG Net EU contribution € 1 811 650,00 Address 2 PLACE DE L'UNIVERSITE 4365 ESCH-SUR-ALZETTE Luxembourg See on map Region Luxembourg Luxembourg Luxembourg Activity type Higher or Secondary Education Establishments Links Contact the organisation Opens in new window Website Opens in new window Participation in EU R&I programmes Opens in new window HORIZON collaboration network Opens in new window Total cost € 1 811 650,00 Beneficiaries (1) Sort alphabetically Sort by Net EU contribution Expand all Collapse all UNIVERSITE DU LUXEMBOURG Luxembourg Net EU contribution € 1 811 650,00 Address 2 PLACE DE L'UNIVERSITE 4365 ESCH-SUR-ALZETTE See on map Region Luxembourg Luxembourg Luxembourg Activity type Higher or Secondary Education Establishments Links Contact the organisation Opens in new window Website Opens in new window Participation in EU R&I programmes Opens in new window HORIZON collaboration network Opens in new window Total cost € 1 811 650,00