Effects of zero-point energy on anharmonic thermophysical properties of zinc

The temperature dependence of anharmonic phenomenon in zinc was studied from 15 K to 690 K by single-crystal inelastic neutron scattering and computer simulations. Diffuse features were observed in the experimental spectra and were shown to be a consequence of phonon-phonon interactions. The diffuse intensity at 15 K is attributed to the anharmonic coupling of zero-point motions. Large-scale Path Integral Molecular Dynamic (PIMD) simulations with machine learning interatomic potentials were used to obtain mode-projected autocorrelation function for direct comparison with experimental vibrational spectrum at low temperatures and with classical MD simulations. The phonon branches responsible for the formation of diffuse intensity were identified. PIMD simulations with NPT ensembles and the stochastic temperature-dependent effective potential method with zero-point contributions showed large effects on the thermal expansion of zinc at low temperatures.