Importance of inclusion of the effect of s electrons into bond-order potentials for transition bcc metals with d-band mediated bonding
Importance of inclusion of the effect of s electrons into bond-order potentials for transition bcc metals with d-band mediated bonding
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将 s 电子的影响纳入具有 d 能带介导键合的过渡 bcc 金属的键序电势中的重要性
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
V. Vitek
中科院分区：
文献类型：
--
作者：
Yi;M. Mrovec;V. Vitek
在键序势（BOPs）的过渡金属只有d电子介导的键是明确的，并使用Slater-Koster dd键积分的结合能的共价部分进行评估。然而，s电子的影响与轨道中心的原子相邻的相应的dd键不一定可以忽略不计。如Nguyen-Manh等人（2000 Phys.Rev.Lett. 854136），这可以通过筛选DD键积分来考虑。在最近的论文（Lin et al 2014 Model.模拟。Mater. Sci. Eng.22034002），dd键积分使用投影方案确定，该投影方案利用在基于密度泛函理论（DFT）的计算中给出电子波函数的最佳表示的原子轨道（Madsen等人，2011 Phys. Rev. B 834119），并且推断在这种情况下已经包括s电子的影响。在本文中，我们分析了这一假设，通过比较研究采用BOP与未屏蔽和屏蔽DD键积分。在所有情况下，结果与基于DFT和/或实验的计算进行比较。研究了体心立方晶格的交替结构，通过连续畸变构型将体心立方结构与面心立方结构、简单立方结构、体心四面体结构和六方结构连接起来的转换路径，以及γ-表面的计算，都发现对键积分的屏蔽不敏感。另一方面，当键积分被屏蔽时，空位的形成能得到改善，计算的声子色散谱更好地再现了实验观察到的。最重要的是，位错核心结构和位错滑移是显着不同的，没有和筛选的dd键积分。后者导致一个更好的协议与现有的实验。这些研究结果表明，s电子对dd键的影响，模拟相应的键积分的筛选，是最不显着的晶格时，扭曲远离理想的体心立方结构均匀，即使这样的失真是大的。另一方面，当畸变是局部的和不均匀的时，dd键积分的屏蔽的影响是显著的。在本文提出的研究中，这种局部不均匀性发生时，声子传播通过晶格，在点缺陷和位错的核心。
In bond-order potentials (BOPs) for transition metals only the bonding mediated by the d electrons is included explicitly and the covalent part of the cohesive energy is evaluated using Slater–Koster dd bond integrals. However, the effect of s electrons with orbitals centered on atoms neighboring the corresponding dd bond is not necessarily negligible. As shown in Nguyen-Manh et al (2000 Phys. Rev. Lett. 85 4136) this can be taken into account via screening of the dd bond integrals. In a recent paper (Lin et al 2014 Model. Simul. Mater. Sci. Eng. 22 034002) the dd bond integrals were determined using a projection scheme utilizing atomic orbitals that give the best representation of the electronic wave functions in the calculations based on the density functional theory (DFT) (Madsen et al 2011 Phys. Rev. B 83 4119) and it was inferred that in this case the effect of s electrons was already included. In this paper we analyze this hypothesis by comparing studies employing BOPs with both unscreened and screened dd bond integrals. In all cases results are compared with calculations based on DFT and/or experiments. Studies of structures alternate to the bcc lattice, transformation paths that connect the bcc structure with fcc, simple cubic (sc), body centered tetragonal (bct) and hcp structures via continuously distorted configurations and calculations of γ-surfaces were all found to be insensitive to the screening of bond integrals. On the other hand, when the bond integrals are screened, formation energies of vacancies are improved and calculated phonon dispersion spectra reproduce the experimentally observed ones much better. Most importantly, dislocation core structure and dislocation glide are significantly different without and with screening of dd bond integrals. The latter lead to a much better agreement with available experiments. These findings suggest that the effect of s electrons on dd bonds, emulated by the screening of corresponding bond integrals, is the least significant when the lattice is distorted away from the ideal bcc structure homogeneously even if such distortion is large. On the other hand, when the distortion is local and inhomogeneous the impact of screening of the dd bond integrals is significant. In the studies presented in this paper such local inhomogeneities occur when phonons propagate through the lattice, at point defects and in the cores of dislocations.
影响因子：
0.8
作者：
T. Hammerschmidt;R. Drautz;D. Pettifor
通讯作者：
T. Hammerschmidt;R. Drautz;D. Pettifor
DOI：
10.1088/0965-0393/22/3/034002
发表时间：
2014-04
影响因子：
1.8
作者：
Yi-Shen Lin;M. Mrovec;V. Vitek
通讯作者：
Yi-Shen Lin;M. Mrovec;V. Vitek