文章信息/Info

Title:

First-principles thermodynamics at finite temperatures: Perspective on ordered and disordered phases

作者:

商順利;  王義;  劉梓葵

賓夕法尼亞州立大學 材料科學與工程系, 美國 賓夕法尼亞州大學城, PA 16802

Author(s):

ShunLi Shang;  Yi Wang;  and Zi-Kui Liu

Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

DOI:

10.7502/j.issn.1674-3962.2015.04.06

文獻標志碼:

A

摘要:

第一原理計算一個懸而未決的難題是預測無序相在有限溫度下的熱力學性能。我們指出該難題的最新解決思路是采用可以處理微觀組態的配分函數方法，該方法已成為處理只有一種微觀組態構成的有序相以及有多種微觀組態構成的無序相的關鍵。結合第一原理聲子計算和準簡諧近似可以有效地預測任意一個給定微觀組態的熱力學性質。本文總結了我們在第一原理熱力學方面的最新研究進展并具體給出了有序相方面的例子：Li2S, hcp Mg和fcc Ni、以及無序相方面的例子：Cu2ZnSnS4 (CZTS) 和fcc Ce。本文同時指出：（i）從常用的“相”擴展到“微觀組態”開辟了一條定量研究材料相變、熱膨脹等異常性能的新途徑，而這些異常性能的起源可以追溯到“微觀組態構型熵”；并且（ii）這些微觀組態也可以認為是材料基因組的基本組成模塊。

Abstract:

A longstanding issue of first-principles calculations is to predict thermodynamic properties for a disordered phase at finite temperatures. Here, we shows that a recent advance for this issue is the partition function approach in terms of microstates, which is the key for both ordered phase with one primary microstate and disordered phase consisting of two and more noticeable microstates. For a given microstate, first-principles phonon calculations in terms of the quasiharmonic approach provide a practical pathway to predict its thermodynamic properties. In the present paper, a summary of properties predicted at finite temperatures is presented, and examples are given for ordered phases of anti-fluorite Li2S, hcp Mg, and fcc Ni as well as disordered phases of Cu2ZnSnS4 (CZTS) and fcc Ce. It is shown that (i) the extension from “phase” to “microstate” opens an avenue to quantitatively tailor anomalous properties such as phase transition and thermal expansion anomaly, and these anomalies are traceable from the microstate configurational entropy, and (ii) these microstates can be considered as the building blocks, i.e., the genome, of materials.