从密度函数理论计算得出的元素晶体的平均内部潜力:高效计算和趋势
Avi Auslender1, Nivedita Pandey1, Amit Kohn1
1Department of Materials Science and Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.
Ultramicroscopy
|October 12, 2023
概括
我们提出了一种更快的计算方法来确定晶体的平均内部电位 (V0),这对于电子显微镜至关重要. 这种方法可以解释原子结合,比以前的方法提供更准确的V0值.
科学领域:
- 固态物理 固态物理
- 材料科学是一种材料科学.
- 计算化学是一种计算化学.
背景情况:
- 平均内部电位 (V0) 对电子显微镜至关重要,但实验值往往不同意.
- 现有的理论方法往往忽略了原子结合或是计算密集型.
研究的目的:
- 通过密度函数理论 (DFT) 引入一种更快的计算方法来计算V0.
- 为44种元素固体提供准确的V0值,包括超出独立原子近似的量子力学计算.
- 调查表面终点对V0的影响,并探索与其他材料属性的相关性.
主要方法:
- 开发了一个更快的DFT实现,使用投影机增强波方法和输出文件的后处理.
- 对44种基本固体进行计算的V0.
- 分析了V0对表面终点的依赖性,并将V0与质量密度和磁性易感性进行比较.
主要成果:
- 计算了44个元素固体的V0,准确度提高,包括首次超出独立原子近似的量子力学计算.
- 由于不同的表面终点,观察到超过3V的V0差异,强调对边界条件的敏感性.
- 建立了V0和质量密度之间的线性相关性,并证明了V0在近似磁性易感性和计算原子散射幅度方面的实用性.
结论:
- 开发的DFT方法提供了一种计算效率高,准确的方法来确定平均内部潜力.
- 平均内电位对表面效应敏感,其值与密度和磁性敏感性等基本材料特性相关.
- 这项工作为电子显微镜和材料表征提供了宝贵的工具.
相关概念视频
02:58Crystal Field Theory - Octahedral Complexes
26.6K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.6K
02:54Trends in Lattice Energy: Ion Size and Charge
23.9K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
23.9K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
42.7K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
42.7K
03:08Atomic Radii and Effective Nuclear Charge
51.7K
The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number and distribution of electrons in their valence shells.
51.7K
02:46Electron Configurations
16.7K
Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest energy available), Pauli exclusion principle (no two electrons can have the same set of four quantum numbers), and Hund’s rule of maximum multiplicity (whenever possible, electrons retain unpaired spins in degenerate orbitals).
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
16.7K
01:17Theory of Metallic Conduction
1.3K
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
1.3K