English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The vibrational entropy of a solid at finite temperature is investigated fromthe perspective of information theory. Ab initio molecular dynamics (AIMD)simulations generate ensembles of atomic configurations at finite temperaturefrom which we obtain the $N$-body distribution of atomic displacements,$\rho_N$. We calculate the information-theoretic entropy from the expectationvalue of $\ln{\rho_N}$. At a first level of approximation, treating individualatomic displacements independently, our method may be applied usingDebye-Waller B-factors, allowing diffraction experiments to obtain an upperbound on the thermodynamic entropy. At the next level of approximation wecorrect the overestimation through inclusion of displacement covariances. Weapply this approach to elemental body-centered cubic sodium and face-centeredcubic aluminum, showing good agreement with experimental values above the Debyetemperatures of the metals. Below the Debye temperatures we extract aneffective vibrational density of states from eigenvalues of the covariancematrix, and then evaluate the entropy quantum mechanically, again yielding goodagreement with experiment down to low temperatures. Our method readilygeneralizes to complex solids, as we demonstrate for a high entropy alloy.Further, our method applies in cases where the quasiharmonic approximationfails, as we demonstrate by calculating the HCP/BCC transition in Ti.

Vibrational entropy of crystalline solids from covariance of atomic displacements