Objective Hydrogen is the simplest and most abundant element in the universe. It exists under extreme conditions in stars and planets. Nuclear fusion, requires creating such extreme temperature and pressure on earth. Lightweight storage of hydrogen in condensed form would unleash its potential as a fuel. The behaviour of a collection of protons and electrons presents an iconic challenge in fundamental physics.Diamond anvil cells (DAC) recently generated pressures above 400GPa, accessing conditions where the mechanical work of compression equals the chemical bonding energy. Most elements undergo dramatic structural changes in this regime, and rival predictions for hydrogen include molecular and atomic metals, superfluidity, superconductivity and one-dimensional melting. Yet when the new phase IV was discovered in 2011, it was none of these things: it was a totally unexpected complex molecular insulator. At these conditions experimental data is sparse: we must exploit it to the fullest extent, yet previous theoretical work has concentrated on routine density functional theory (DFT) simulation producing unmeasurable predictions. I will conduct a programme combining neutron scattering and Raman spectroscopy with theory and simulation focused on measurable quantities. This will require developing and implementing heuristic theories which do not currently exist.I will develop methods to find free energy, theory to extract Raman frequencies and linewidths from simulation, and techniques to determine the signature from entanglement of quantum rotors. This requires a thorough re-examination of the quantum scattering processes in the framework of DFT, including the interaction timescale and in metals, and a full quantum treatment of indistinguishable nuclei.Thus HECATE will be uniquely placed not only to produce new phases of hydrogen, but to reliably identify what has been found. Fields of science natural sciencesphysical sciencesnuclear physicsnuclear fusion Keywords Hydrogen Pressure Free energy electronic structure Programme(s) H2020-EU.1.1. - EXCELLENT SCIENCE - European Research Council (ERC) Main Programme Topic(s) ERC-ADG-2015 - ERC Advanced Grant Call for proposal ERC-2015-AdG See other projects for this call Funding Scheme ERC-ADG - Advanced Grant Host institution THE UNIVERSITY OF EDINBURGH Net EU contribution € 2 277 206,00 Address OLD COLLEGE, SOUTH BRIDGE EH8 9YL Edinburgh United Kingdom See on map Region Scotland Eastern Scotland Edinburgh 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 € 2 277 206,00 Beneficiaries (1) Sort alphabetically Sort by Net EU contribution Expand all Collapse all THE UNIVERSITY OF EDINBURGH United Kingdom Net EU contribution € 2 277 206,00 Address OLD COLLEGE, SOUTH BRIDGE EH8 9YL Edinburgh See on map Region Scotland Eastern Scotland Edinburgh 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 € 2 277 206,00