Defects in materials significantly alter their electronic and structural properties,which affect the per-formance of electronic devices,structural alloys,and functional materials.However,calculating all the possible d...Defects in materials significantly alter their electronic and structural properties,which affect the per-formance of electronic devices,structural alloys,and functional materials.However,calculating all the possible defects in complex materials with conventional Density Functional Theory(DFT)can be compu-tationally prohibitive.To enhance the efficiency of these calculations,we interfaced Density Functional Tight Binding(DFTB)with the Clusters Approach to Statistical Mechanics(CASM)software package for the first time.Using SiC and ZnO as representative examples,we show that DFTB gives accurate results and can be used as an efficient computational approach for calculating and pre-screening formation ener-gies/convex hulls.Our DFTB+CASM implementation allows for an efficient exploration(up to an order of magnitude faster than DFT)of formation energies and convex hulls,which researchers can use to probe other complex systems.展开更多
The blossoming trade war betwee China and the United States has just been warmed-up a notch. A new body comprising seven US-based solar cell and module makers calling
天然状态下水合物生成后往往填充于沉积物土骨架孔隙中或黏结于相邻土颗粒之间,对沉积物具有填充和黏结作用,改变了沉积物原有孔隙比和密度,影响了沉积物的物理力学特性,因此在描述含水合物沉积物的力学和变形特性时需考虑水合物填充和...天然状态下水合物生成后往往填充于沉积物土骨架孔隙中或黏结于相邻土颗粒之间,对沉积物具有填充和黏结作用,改变了沉积物原有孔隙比和密度,影响了沉积物的物理力学特性,因此在描述含水合物沉积物的力学和变形特性时需考虑水合物填充和黏结作用的影响。基于黏土和砂土的统一临界状态本构模型(clay and sand model,简称CASM),结合水合物侵入孔隙的致密化特性,通过提出等效孔隙比来反映水合物的填充作用;同时引入黏聚强度来反映水合物对沉积物的黏结作用;并利用状态参数来反映土体的应力状态和剪胀性,采用非相关联流动法则,进而建立能够描述水合物填充和黏结作用的含水合物沉积物弹塑性本构模型。通过与室内试验结果和已有本构模型对比,表明所提模型能较好地模拟含水合物沉积物的应力-应变关系,可有效地描述水合物含量、有效围压对沉积物的强度、刚度、剪胀性等力学特性的影响规律。展开更多
基金supported by the U.S.Department of Energy,Na-tional Energy Technology Laboratory(NETL),under Award No.DE-FE0030582.
文摘Defects in materials significantly alter their electronic and structural properties,which affect the per-formance of electronic devices,structural alloys,and functional materials.However,calculating all the possible defects in complex materials with conventional Density Functional Theory(DFT)can be compu-tationally prohibitive.To enhance the efficiency of these calculations,we interfaced Density Functional Tight Binding(DFTB)with the Clusters Approach to Statistical Mechanics(CASM)software package for the first time.Using SiC and ZnO as representative examples,we show that DFTB gives accurate results and can be used as an efficient computational approach for calculating and pre-screening formation ener-gies/convex hulls.Our DFTB+CASM implementation allows for an efficient exploration(up to an order of magnitude faster than DFT)of formation energies and convex hulls,which researchers can use to probe other complex systems.
文摘The blossoming trade war betwee China and the United States has just been warmed-up a notch. A new body comprising seven US-based solar cell and module makers calling
文摘天然状态下水合物生成后往往填充于沉积物土骨架孔隙中或黏结于相邻土颗粒之间,对沉积物具有填充和黏结作用,改变了沉积物原有孔隙比和密度,影响了沉积物的物理力学特性,因此在描述含水合物沉积物的力学和变形特性时需考虑水合物填充和黏结作用的影响。基于黏土和砂土的统一临界状态本构模型(clay and sand model,简称CASM),结合水合物侵入孔隙的致密化特性,通过提出等效孔隙比来反映水合物的填充作用;同时引入黏聚强度来反映水合物对沉积物的黏结作用;并利用状态参数来反映土体的应力状态和剪胀性,采用非相关联流动法则,进而建立能够描述水合物填充和黏结作用的含水合物沉积物弹塑性本构模型。通过与室内试验结果和已有本构模型对比,表明所提模型能较好地模拟含水合物沉积物的应力-应变关系,可有效地描述水合物含量、有效围压对沉积物的强度、刚度、剪胀性等力学特性的影响规律。
