Neutron Scattering and Neural Network Elucidate Nuclear Quantum Effects in Ammonia
Scientific Achievement
A long-standing mystery concerning properties of ammonia (NH3) was solved by integrating neutron scattering and neural networks. Anharmonicity induced by nuclear quantum effects (NQEs) is identified as the origin of the drastically softened vibrational modes.
Significance and Impact
Ammonia is indispensable in agriculture and green chemistry. Its thermodynamical and vibrational properties are closely linked, yet accurate understanding of vibrational dynamics in ammonia remained elusive until now. The computational framework developed and used in the current work can be generalized to study various materials.
Research Details
- Neural network interatomic potentials are developed for ammonia.
- Thermostatted ring-polymer molecular dynamics is used to include NQEs in the simulated vibrational spectra. Comparison with spectra measured on VISION and SEQUOIA reveals enormous anharmonicity caused by NQEs.
“Neutron scattering and neural-network quantum molecular dynamics investigation of the vibrations of ammonia along the solid-to-liquid transition,”
Nature Communications, 15, 3911 (2024)
https://doi.org/10.1038/s41467-024-48246-9
