How much of the latent heat of melting is explained by vibrational dynamics?

Atomic vibrations dominate the entropy of solids and liquids. Less is known about the latent heat, L=T_mΔS, which is determined by the melting temperature, T_m, and the entropy of fusion, ΔS. Here, we used inelastic neutron scattering to probe changes in vibrations of Ge, Sn, Pb, Bi, and Zn on an energy scale of ~5-50 meV through the melt. Our analyses, informed by vibrational-transit theory and supported by machine-learned molecular dynamics simulations, show a distinct contribution of atomic dynamics for each element. In Ge, which has an anomalously high entropy of fusion, preliminary results show a vibrational component of ~50%. In Bi, Sn, Pb, and Zn, the role of atomic motion decreases approximately in accordance with the total entropy of fusion to a value of ~5%. We will discuss what these findings imply for the physics of melting by taking a decomposition of the latent heat into electronic, configurational, and vibrational components.