In this paper, we employ evolutionary algorithm along with the full-potential density functional theory (DFT) computations to perform a comprehensive search for the stable structures of stoichiometric (WS2)n nano-clusters (n=1-9), within three different exchange-correlation functionals. Our results suggest that n=3, 5, 8 are possible candidates for the low temperature magic sizes of WS2 nano-clusters while at temperatures above 600 Kelvin, n=5 and 7 exhibit higher relative stability among the studied systems. The electronic properties and energy gap of the lowest energy isomers were computed within several schemes, including semilocal PBE and BLYP functionals, hybrid B3LYP functional, many body based DFT+GW approach, and time dependent DFT calculations. Vibrational spectra of the lowest lying isomers, computed by the force constant method, are used to address IR spectra and thermal free energy of the clusters. Time dependent density functional calculation in real time domain is applied to determine the full absorption spectra and optical gap of the lowest energy isomers of the WS2 nano-clusters.
Interplay between structure and magnetism in $Mo_{12} S_9 I_9$ nanowires
我们用从头算密度泛函方法研究了Mo $_{12}$ S $_{9}$ I $_{9}$纳米线的平衡几何构型和电子结构.这些异常稳定的纳米线的骨架由刚性的官能化Mo八面体组成,通过柔性的双稳态硫桥连接。这种结构灵活性转化为几乎没有能源成本的情况下拉伸高达约20%的能力。纳米线从导体转变为窄隙磁性半导体,其结构异构体之一。
AtomComposer: Discovering Chemical Space from First Principles with Reinforcement Learning
Dept. of Energy Conversion and Storage, Technical University of Denmark(丹麦技术大学能源转换与存储系);Dept. of Applied Mathematics and Computer Science, Technical University of Denmark(丹麦技术大学应用数学与计算机科学系);Pioneer Center for Accelerating P2X Materials Discovery (CAPeX), Kgs. Lyngby, Denmark(加速P2X材料发现的先锋中心(CAPeX),Lyngby,丹麦)
Precursor stoichiometry controls dopant structure, defect chemistry, and valence in Mn-doped ZnGa$_2$O$_4$ nanocrystals
HUN-REN Wigner Research Centre for Physics(匈牙利科学院维格纳物理研究中心);Institute for Solid State Physics and Optics(凝聚态物理与光学研究所);Budapest University of Technology and Economics(布达佩斯科技经济大学);University of Notre Dame(圣母大学)
Oxygen vacancy mediated cubic phase stabilization at room temperature in pure nano-crystalline Zirconia films: A combined experimental and first-principles based investigation
采用密度泛函紧束缚和经典分子动力学模拟研究了N=2-55的平面碳纳米团簇$C_{N}$的结构变形和熔化.不同团簇的最小能量构型被用作研究温度对碳线(N $<$ 6)、碳环(5 $<$ N $<$ 19)和石墨烯纳米片中键断裂/旋转的影响的起始构型。环(石墨烯纳米片)越大,具有环到线(完美到缺陷)转变结构的转变温度(熔点)越高。熔点是通过使用键能,林德曼标准,和比热。我们发现氢钝化的石墨烯纳米片(C $_{N}$ H $_M$)具有较大的熔融温度,其尺寸依赖性小得多。石墨烯纳米片中的边缘在熔化发生之前的加热期间表现出几种不同的亚稳构型(异构体)。
Exploration of potential and free energy surfaces of the neutral Be$_4$B$_{8}$ chiral clusters and their stabilities at finite temperatures
最低能量的结构,异构体的分布,以及它们的分子性质显着依赖于几何形状和温度。DFT方法下的总能量计算通常在零温度下进行;因此,熵对总能量的贡献被忽略,即使功能材料在有限温度下工作。在本研究中,一个特定的Be $_4$ B $_8$异构体在温度T的发生概率估计的量子统计力学和纳米热力学的框架内。为了找到一个列表中所有可能的低能量手性和非手性结构,一个详尽的和有效的探索的潜在/自由能表面进行采用多级多步全局遗传算法搜索耦合到DFT。此外,我们讨论了能量排序的结构计算在DFT水平上对单点能量计算在CCSD(T)水平的理论。将计算出的每种异构体的VCD/IR光谱乘以它们在温度T下的相应玻尔兹曼权重;然后,将它们加在一起以产生最终的玻尔兹曼加权光谱。此外,我们提出了化学键分析使用自适应自然密度分区方法在手性假定的全球最小值。过渡态结构和对映异构体-对映异构体和对映异构体-非手性活化能随温度的变化表明,在739 K温度下发生了从吸能型到放能型的反应。
CO oxidation on Pd(100) at technologically relevant pressure conditions: A first-principles kinetic Monte Carlo study
近年来,氧化物的形成对过渡金属多相氧化催化活性的影响引起了热烈的讨论。在更贵的过渡金属(如Pd、Pt或Ag)上,常见的本体氧化物的低稳定性主要表明亚纳米薄氧化物膜(所谓的表面氧化物)作为潜在的候选物,其可以在代表技术氧化催化的气相条件下稳定。我们解决了这个问题的Pd(100)模型催化剂表面的第一性原理动力学蒙特卡罗(kMC)模拟,评估稳定的表征(sqrt{5} x sqrt{5})R27表面氧化物在稳态CO氧化。我们的研究结果表明,在环境压力条件下,表面氧化物是稳定的表面CO:O2分压比附近的催化最相关的化学计量进料(p(CO):p(O2)= 2:1)。精确的值敏感地取决于温度,使得局部压力和温度波动都可能在环境化学计量条件下的稳态操作期间引起氧化物相的连续形成和分解。
Band Structure Modulation of ZrO2 Nanoparticles for Control of CO Adsorption Properties: A Combined Density Functional Theory - Density Functional Tight Binding Study
School of Materials and Chemical Technology, Institute of Science Tokyo(东京科学大学材料化学技术学院);RIKEN Center for Computational Science(理化学研究所计算科学中心);Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada(加查马达大学数学与自然科学学院化学系)