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[综合交流] 有关文献中浓度分布判断的疑问

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来自18年的一篇Angew:"An Efficient Anti-poisoning catalyst against SOx, NOx and POx: P, N- doped Carbon for Oxygen Reduction in Acidic Media"(doi:10.1002/anie.201808383)
Fig.3 b-c和f-g,为什么浓度分布大的地方就为杂原子的位点呢?望各位前辈指点迷津。

以下是在SI中的计算细节:
For DFT calculations all MD simulations were carried out using LAMMPS MOLECULAR Dynamics Simulator. A three dimensional periodic simulation cell size of 2012.812 Å3 was created. The graphene sheets were positioned parallel to the xy plane and were separated by 6.5 Å in the middle of the box. The Graphene slab model contains 47, 5, and 2 molecules of water, HClO4, SOx or NOx. The mole ratio of HClO4 is 0.1, and the mole ratio of SOx or NOx is 0.05. The density of water layer was 1 g cm-3. The canonical (NVT) ensemble was employed by Nosé-Hoover thermostat method at a constant temperature of 300K (SMASS ≥0). The simulations generated 200 ps of equilibrated trajectories with 0.5 fs as time step.
The concentration profile was obtained by calculating the atomic density distribution of the 3D periodic structure parallel to the coordinate axis. The relative concentration is defined as the ratio of the number of atoms in the unit volume perpendicular to the axis direction to the number of atoms contained in the unit volume of the amorphous cell. Thus, the unit of the vertical axis (relative concentration) is dimensionless. The distance means the distance from the specified plane which is perpendicular to the unit for the relative concentration calculation.
Specifically, in Figure 3a-h, the distance means the numerical measurement form the graphene surface (along the Z-axis). And in Figure 3 i-j, the distance means the numerical measurement along the X-axis, i.e., parallel to the graphene surface to identify the relative position on graphene.


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发表于 Post on 2024-11-12 16:32:43 | 只看该作者 Only view this author
和无杂原子掺杂的完美石墨烯里的浓度分布一对比应该就很明显了

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 楼主 Author| 发表于 Post on 2024-11-13 10:58:55 | 只看该作者 Only view this author
yxdd98 发表于 2024-11-12 16:32
和无杂原子掺杂的完美石墨烯里的浓度分布一对比应该就很明显了

好的,谢谢指导。这种杂原子石墨烯表面的杂原子电荷应该如何确定呢?给的力场计算完美石墨烯显0电荷,杂原子会让其带电吗?

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发表于 Post on 2024-11-13 16:15:20 | 只看该作者 Only view this author
ch_pzq1102 发表于 2024-11-13 10:58
好的,谢谢指导。这种杂原子石墨烯表面的杂原子电荷应该如何确定呢?给的力场计算完美石墨烯显0电荷,杂 ...

电负性不同应该会导致电子结构变化,但具体原子电荷能变化多少、影响范围有多大就不好说了,得实际算下,可以用CP2K计算REPEAT电荷试下

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