Comparative first-principles study of elastic constants of covalent and ionic materials with LDA,GGA,and meta-GGA functionals and the prediction of mechanical hardness  

作　　者：XING WanDong MENG FanYan NING JinLiang SUN JianWei YU Rong 

机构地区：[1]Department of Physics,University of Science and Technology Beijing,Beijing 100083,China [2]National Center for Electron Microscopy in Beijing,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China [3]Department of Physics and Engineering Physics,Tulane University,New Orleans,LA 70118,USA

出　　处：《Science China(Technological Sciences)》2021年第12期2755-2761,共7页中国科学（技术科学英文版）

基　　金：the National Natural Science Foundation of China(Grant Nos.51788104,51871021 and 51525102);the Fundamental Research Funds for the Central Universities(Grant No.FRF-BD-19-017A)。

摘　　要：Accurate prediction of single-crystal elastic constants is critical for materials design and for understanding phase transition and elastic interactions in materials.In this work,the accuracy of elastic constants calculated with three density functional approximations has been compared,including the local density approximation(LDA),the generalized gradient approximation(GGA),and the recently developed strongly constrained and appropriately normed(SCAN)meta-GGA.The results show that SCAN and PBE describe elastic constants better than LDA.The strong correlation between the mechanical hardness and the stiffness of the softest eigenmode(SSE)has been given for above three density functionals.The correlation is capable of predicting accurately the hardness of covalent,ionic,and mixed covalent-ionic crystals,and providing us a convenient indicator for the discovery of hard or superhard materials.

关 键 词：hardness indicator elastic constants stiffness of softest eigenmode superhard materials 

分 类 号：TB30[一般工业技术—材料科学与工程]