The melting curve of Sodium: a theoretical approach

TL;DR

This paper introduces a theoretical model to predict how pressure influences the melting temperature of sodium, based on phonon vibrations and their resonance with lattice vibrations, validated by experimental data.

Contribution

A novel theoretical framework linking phonon behavior and pressure effects to melting temperature, validated through experiments on sodium.

Findings

Model accurately predicts sodium melting curve under pressure

Phonon-lattice resonance explains melting temperature changes

Pressure reduces anharmonic vibrations, affecting melting point

Abstract

New model describing the pressure effect on the melting temperature is proposed by using four assumptions. One, the average wavelength of the phonon vibration at the Debye temperature corresponds to the length of the unit cell. Two, the phonon vibration at the melting temperature is in self-resonance with the lattice vibration of the surface atomic/molecular layer. Three, the phonon wavelength ratio of the Debye and the melting temperature does not be affected by the pressure. Four the pressure reduces the anharmonic part of the vibration. The relevant equations are derived and tested against the experiments of sodium with positive result.