Nuclear Quantum Effects Enter the Mainstream

DIPC Seminars

Matthew Krzystyniak, STFC Rutherford Appleton Laboratory, UK
Online seminar, Donostia International Physics Center
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Nuclear Quantum Effects Enter the Mainstream Neglecting nuclear quantum effects has become one of the largest sources of error, especially when systems containing light atoms are treated using current state‑of‑the-art descriptions of chemical interactions. Over the past decade, this realization has spurred a series of methodological advances that have dramatically reduced the cost of including these important physical effects in the description of the structure and dynamics of chemical systems. Here, I will discuss how these developments are now allowing nuclear quantum effects to become a mainstream feature of materials science. An experimental technique that has greatly facilitated these advances and led to new insights into phenomena that are relevant to different areas of science — from biochemistry to condensed matter — is the Neutron Compton scattering (NCS). NCS is a unique experimental technique made possible by the development of epithermal neutron sources, such as the ISIS source of the Rutherford Appleton Laboratory in the UK. The measurement of nuclear momenta by high-energy neutron Compton scattering relies on the fact that the energy and momentum transferred in the scattering process are sufficiently large, such that the so-called impulse approximation (IA) is an accurate starting point. In the IA limit, the dynamic structure factor measured in NCS for a given nucleus is determined by the nuclear momentum distribution (NMD). Nuclear quantum effects, such as nuclear zero-point energy, delocalization, and tunnelling, determine the shapes of NMDs. Since its birth, the NCS technique has been employed to study mostly proton momentum distributions in quantum fluids and solids, metal hydrides and gas and charge-storage media. Recent NCS technique developments have challenged this paradigm by paving the ground for the concurrent application of four techniques at one beamline. Neutron diffraction, transmission, neutron Compton scattering, and neutron gamma Dopplerimetry, all under the umbrella of the Mass-resolved Neutron Spectroscopy (MANSE), offer the prospects of accessing NMDs of nuclides far heavier than the proton. I will present some examples of recent MANSE work advocating the concurrent application of different neutron scattering techniques at one beamline, all augmented by modern ab initio tools for better characterization of nuclear chemical dynamics in the solid-state and molecular systems. Host: Felix Fernandez Alonso **ZOOM: ** **YouTube: **