We assess the performance of recent density functionals for the exchange-correlation energy of a nonmolecular solid, by applying accurate calculations with the GAUSSIAN, BAND, and VASP codes to a test set of 24 solid metals and non-metals. The functionals tested are the modified Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol GGA), the second-order GGA (SOGGA), and the Armiento-Mattsson 2005 (AM05) GGA. For completeness, we also test more-standard functionals: the local density approximation, the original PBE GGA, and the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA. We find that the recent density functionals for solids reach a high accuracy for bulk properties (lattice constant and bulk modulus). For the cohesive energy, PBE is better than PBEsol overall, as expected, but PBEsol is actually better for the alkali metals and alkali halides. For fair comparison of calculated and experimental results, we consider the zero-point phonon and finite-temperature effects ignored by many workers. We show how Gaussian basis sets and inaccurate experimental reference data may affect the rating of the quality of the functionals. The results show that PBEsol and AM05 perform somewhat differently from each other for alkali metal, alkaline earth metal and alkali halide crystals (where the maximum value of the reduced density gradient is about 2), but perform very similarly for most of the other solids (where it is often about 1). Our explanation for this is consistent with the importance of exchange-correlation nonlocality in regions of core-valence overlap.
Assessing the performance of the recent non-empirical semilocal density functionals on describing the lattice constants, bulk moduli and cohesive energies of alkali, alkaline-earth, and transition metals
在最近开发的元GGA(元广义梯度近似)半局域交换相关泛函的框架内,研究了碱金属、碱土金属和过渡金属的体性质(晶格常数、体模量和结合能)。为了建立元GGA泛函的适用性,广泛性和准确性,我们还把PBE(Perdew-Burke-Ernzerhof)和PBESol(PBE reparametrized for solids)泛函的结果。本论文的有趣的特点是,它测量最近开发的TM(陶-莫)和TMTPSS(TM交换与陶-Perdew-Staroverov-Scuseria(TPSS)相关)和SCAN(强约束和适当赋范)泛函描述上述属性的准确性。本系统的调查表明,TM是准确的,而在描述的晶格常数的内聚能和体积模量的准确性是偏向PBE和TPSS泛函。
Synergetic Enhancement on Bulk and Grain Boundary Ionic Conduction of Mg Doped High-Entropy NASICON-Type Solid Electrolyte for Solid-State Na+ Batteries by Spray Flame Synthesis
A solid-solution approach for room-temperature bulk plasticity in KTa1-xNbxO3
Karlsruhe Institute of Technology(卡尔斯鲁厄理工学院);Southern University of Science and Technology(南方科技大学);Charles University(查理大学);Qilu University of Technology (Shandong Academy of Sciences)(齐鲁工业大学(山东省科学院))
Pseudo-ternary LiBH4-LiCl-P2S5 system as structurally disordered bulk electrolyte for all-solid-state lithium batteries
研究了LiBH_4-LiCl-P_2S_5混合体系在全固态电池中的性能。所研究的材料在加热到601 ℃以上时发生非晶化,伴随着有利于电池电解质应用的Li+电导率增加。在室温下测得的离子电导率为10- 3Scm-1,非晶化后的激活能为0.40(2)eV。材料的结构分析和表征表明,BH 4基团和PS 4可能属于相同的分子结构,其中Cl离子相互作用以容纳结构单元。由于其导电性,延展性和电化学稳定性(高达5 V,Au vs. Li+/Li),这种新的电解质在使用阴极材料(层状TiS 2,theo.在501 ℃下,以Li为阳极,在12 mA g ~(-1)(0. 05 C-倍率)的电流密度下进行10次循环,容量保持率为93%,循环稳定性良好。通过透射模式的同步加速器X射线衍射进行的进一步先进表征明显有助于更好地了解在中等温度下运行的固态电池电极的(脱)锂过程。
Switching behavior of bulk Fast Ion Conducting AgI-Ag2O-MoO3 glasses with inert electrode
开发高效、快速性能和热稳定的基于碘化银的快速离子传导固体对于电阻开关应用具有极大的兴趣,但仍然存在挑战。金属化的散装,阈值电压曲线的行为组成和腐蚀反应是这些挑战的几个。本文研究了快离子导电玻璃体(AgI)x-(Ag_2O)_25-(MoO_3)_75-x(60 < x < 40)固体的开关行为,以了解惰性电极的开关机理。通过使用惰性电极,开关变成不可逆的记忆型。开关机制是电化学金属化过程。惰性电极抑制离子传质,但对电子转移表现出低势垒,允许阴极金属化反应更快地达到能斯特平衡。该过程中涉及的阳离子在固体结构内的自由体积中传输,并遵循电场驱动的热激活离子跳跃电导模型的Mott-Gurney模型。该模型与热稳定性曲线一起提供了组合物内的窄区域,该组合物具有基于达到阈值电压的不稳定性的更好的开关性能和更少的功率损耗。痕量的阴离子对金属化的贡献是不存在的。此外,阳极氧化涉及导致气泡形成和腐蚀的反应。
Bulk Polycrystalline Ceria Doped Al$_2$O$_3$ and YAG Ceramics for High-Power Density Laser-Driven Solid-State White Lighting: Effects of Crystallinity and Extreme Temperatures
Thermodynamic Relationships for Bulk Crystalline and Liquid Phases in the Phase-Field Crystal Model
我们提出的相场晶体(PFC)模型的自由能和流体静压下的体相的热力学状态变量之间的热力学关系。该关系是基于Larché和Cahn [Larché和Cahn,Acta Metallurgica,第21卷,1051(1973)]的结晶固体的热力学形式推导的。我们应用的关系来检查与不同的PFC模型的输入参数:温度,晶格间距,和PFC序参量,$\bar{n}$的平均值相关的热力学过程。散装结晶固体和液体相之间的平衡条件施加在PFC模型的热力学关系,以获得一个程序,用于确定固-液相共存。由此产生的程序被认为是一致的PFC社区中常用的方法,证明使用的共同切线建设,以确定固-液相共存的PFC模型。最后,我们将该程序应用于八阶拟合(Eighth Order-fit,EQF)PFC模型,该模型已被参数化为体心立方($bcc$)Fe [Jaatinen et al.,Physical Review E 80,031602(2009)],以演示该程序并开发关于PFC输入参数的物理直觉。我们表明,EOF-PFC模型参数化不预测稳定的$bcc$结构的正空位密度。这一结果表明PFC模型的另一种参数化,它需要两体直接关联函数的主峰位置作为$\bar{n}$的函数移动。
Ab initio molecular and solid state studies of Fe$^{II}$ spin cross-over system [Fe(btz)$_2$(NCS)$_2$
本文报道了自旋交叉复合物[Fe(btz)$_{2}$(NCS)$_{2}$ ]的密度泛函理论从头计算,其中3d $^6$ Fe $^{II}$的特征是高自旋态(HS t $_{2g}^4$,e $_g^2$)和低自旋态(LS t $_{2g}^6$,e $_g^0$).红外光谱和拉曼光谱的孤立的分子的结果是补充的结晶固体的电子能带结构特性的充分考虑:评估晶体场效应的状态密度和化学键指定一个特定的作用,Fe $^{II}$的协调领域内的Fe-N相互作用。