Effect of compression in molecular spin-crossover chains

TL;DR

This paper analyzes how external pressure affects the thermodynamic properties of one-dimensional spin-crossover molecular chains using an effective Ising model, deriving exact expressions for key physical quantities.

Contribution

It introduces an analytic approach to study pressure effects on spin crossover in 1D chains using a compressible Ising model, providing exact formulas for several thermodynamic properties.

Findings

Pressure shifts the spin crossover point.

Exact expressions for high spin fraction, correlation, and heat capacity are derived.

Pressure influences the thermodynamic behavior of the molecular chain.

Abstract

In this work, we investigate thermodynamic properties of the one-dimensional (1D) spin-crossover molecular chain being a subject of a constant external pressure. Effective compressible degenerate Ising model is used as a theoretical framework. Using transfer matrix formalism analytic results for the low spin -- high spin crossover were obtained. We derive the exact expressions for the fraction of molecules in the high spin state, correlation function and heat capacity. We provide analysis of parameters region where the spin crossover takes place and demonstrate how pressure changes location of the crossover.