Free Energy of Metals from Quasi-harmonic Models of Thermal Disorder

Metals

Pavel A. Korzhavyi¹  Jing Zhang¹ 

[1] Department of Materials Science and Engineering, KTH Royal Institute of Technology, SE 10044 Stockholm, Sweden;

关键词: quasi-harmonic approximation;    Debye model;    first-principles calculations;    Helmholtz free energy;    thermophysical properties;    cubic metals;   

DOI  :  10.3390/met11020195

来源: DOAJ

【 摘 要 】

A simple modeling method to extend first-principles electronic structure calculations to finite temperatures is presented. The method is applicable to crystalline solids exhibiting complex thermal disorder and employs quasi-harmonic models to represent the vibrational and magnetic free energy contributions. The main outcome is the Helmholtz free energy, calculated as a function of volume and temperature, from which the other related thermophysical properties (such as temperature-dependent lattice and elastic constants) can be derived. Our test calculations for Fe, Ni, Ti, and W metals in the paramagnetic state at temperatures of up to 1600 K show that the predictive capability of the quasi-harmonic modeling approach is mainly limited by the electron density functional approximation used and, in the second place, by the neglect of higher-order anharmonic effects. The developed methodology is equally applicable to disordered alloys and ordered compounds and can therefore be useful in modeling realistically complex materials.

【 授权许可】

Unknown