Two state model for critical points and the negative slope of the melting-curve

Graeme J. Ackland*, Hongxiang Zong, Victor Naden Robinson, Sandro Scandolo, Andreas Hermann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We present a thermodynamic model which explains the presence of a negative slope in the melt curve, as observed in systems as diverse as the alkali metals and molecular hydrogen at high pressure. We assume that components of the system can be in one of two well defined states - one associated with low energy, the other with low volume. The model exhibits a number of measurable features which are also observed in these systems and are therefore expected to be associated with all negative Clapeyron-slope systems: first order phase transitions, thermodynamic anomalies along Widom lines. The melt curve maximum is a feature of the model, but appears well below the pressures where the change in state occurs in the solid: the solid-solid transition is related to the melt line minimum. An example of the model fitted to the electride transition in potassium is discussed.
Original languageEnglish
Article number054120
Pages (from-to)1-11
Number of pages11
JournalPhysical Review B
Issue number5
Publication statusPublished - 30 Aug 2021

Keywords / Materials (for Non-textual outputs)

  • cond-mat.stat-mech
  • cond-mat.other


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