Fragmentation Phase Transition in Atomic Clusters IV -- Liquid-gas transition in finite metal clusters and in the bulk --

TL;DR

This paper demonstrates that phase transitions in finite metal clusters can be accurately characterized within the microcanonical ensemble, revealing properties akin to bulk matter without requiring the thermodynamic limit.

Contribution

It shows that microcanonical analysis captures liquid-gas transition properties in finite metal clusters, linking small system behavior to bulk phase transitions.

Findings

Transition temperature approaches bulk values for ~1000 atoms

Latent heat and surface tension match experimental bulk data

Microcanonical T(E) reveals transition details suppressed in canonical ensemble

Abstract

Within the micro-canonical ensemble phase transitions of first order can be identified without invoking the thermodynamic limit. We show for the liquid-gas transition of sodium, potassium, and iron at normal pressure that the transition temperature, the latent heat as well as the interface surface tension approach for some 1000 atoms the experimental bulk values. No excursion to the thermodynamic limit is neccessary. It is often easier to identify the transition in mesoscopic systems than in the infinite system. It is shown that the microcanonical T(E) contains important information about the transition which becomes suppressed in the canonical ensemble. The implications for our understanding of phase transitions in general are discussed. For these finite metallic systems it is essential to allow for a fragmentation of the system. Our result demonstrates further that microcanonical Metropolis Monte Carlo sampling (MMMC) is well suited to establish the link between the fragmentation phase transition in small systems like nuclei and atomic clusters and the liquid-gas transition of infinite matter.