title: Nuclear quantum effects on the high pressure melting of dense lithium.
abstract: Using a self-developed combination of the thermodynamic integration and the ab initio path-integral molecular dynamics methods, we quantitatively studied the influence of nuclear quantum effects (NQEs) on the melting of dense lithium at 45 GPa. We find that although the NQEs significantly change the free-energies of the competing solid and liquid phases, the melting temperature (Tm) is lowered by only ∼15 K, with values obtained using both classical and quantum nuclei in close proximity to a new experiment. Besides this, a substantial narrowing of the solid/liquid free-energy differences close to Tm was observed, in alignment with a tendency that glassy states might form upon rapid cooling. This tendency was demonstrated by the dynamics of crystallization in the two-phase simulations, which helps to reconcile an important conflict between two recent experiments. This study presents a simple picture for the phase diagram of lithium under pressure. It also indicates that claims on the influence of NQEs on phase diagrams should be carefully made and the method adopted offers a robust solution for such quantitative analyses.
authors: International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors: Yexin
authors: Y
authors: Feng
authors: International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors: Ji
authors: J
authors: Chen
authors: London Centre for Nanotechnology, UCL, London WC1H 0AH, United Kingdom; Department of Physics and Astronomy, University College London, London WC1E6BT, United Kingdom; and Department of Earth Sciences, University College London, London WC1E6BT, United Kingdom.
authors: Dario
authors: D
authors: Alfè
authors: International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors: Xin-Zheng
authors: XZ
authors: Li
authors: International Center for Quantum Materials and School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors: Enge
authors: E
authors: Wang