标题: 有关文献中浓度分布判断的疑问 [打印本页] 作者Author: ch_pzq1102 时间: 2024-11-12 16:24 标题: 有关文献中浓度分布判断的疑问 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 2012.812 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.