The Einstein specific heat model for finite systems

TL;DR

This paper extends Einstein's model of specific heat to finite systems, revealing unique low-temperature behaviors, phase transition phenomena, and chemical potential characteristics relevant for nanoscale materials.

Contribution

It introduces a finite-oscillator version of Einstein's model, highlighting novel thermodynamic behaviors at the nanoscale not present in the traditional infinite system assumption.

Findings

Qualitative low-temperature specific heat description for nanosystems

Chemical potential becomes zero at finite temperatures in finite solids

Emergence of a first-order like phase transition with changing system size

Abstract

The theoretical model proposed by Einstein to describe the phononic specific heat of solids as a function of temperature consists the very first application of the concept of energy quantization to describe the physical properties of a real system. Its central assumption lies in the consideration of a total energy distribution among N (in the thermodynamic limit $N \rightarrow \infty$) non-interacting oscillators vibrating at the same frequency ($\omega$). Nowadays, it is well-known that most materials behave differently at the nanoscale, having thus some cases physical properties with potential technological applications. Here, a version of the Einstein's model composed of a finite number of particles/oscillators is proposed. The main findings obtained in the frame of the present work are: (i) a qualitative description of the specific heat in the limit of low-temperatures for systems with nano-metric dimensions; (ii) the observation that the corresponding chemical potential function for finite solids becomes null at finite temperatures as observed in the Bose-Einstein condensation and; (iii) emergence of a first-order like phase transition driven by varying $N$.