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10 changes: 6 additions & 4 deletions source/_posts/DeePMD_13_12_2024.md
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,9 @@ The development of efficient solid-state electrolytes (SSEs) is crucial for the

The cubic phase A<sub>3</sub>MS<sub>4</sub> (A = Na, K; M = Sb, P) materials have an open three-dimensional framework structure, which is beneficial for the rapid transmission of ions. However, due to the full occupation of the A site by alkali metals and the effect of electrostatic repulsion, it is difficult for them to diffuse to adjacent A sites, so the unmodified materials usually have a very low ionic conductivity. Complex experimental explorations are often time-consuming and laborious, and the technical obstacles in phase synthesis limit the rapid development of potassium solid-state electrolytes.

Molecular dynamics simulation has become an important tool for understanding the properties and mechanisms of solid-state electrolytes. However, the first-principles molecular dynamics simulation (AIMD) is slow in calculation because it needs to continuously solve the Schrödinger equation, and the atom system that can be simulated usually does not exceed 300 - 500 atoms. Due to insufficient sampling, the results of each simulation for the same system at the same temperature may vary, as has been shown in our previous article.1 This study focuses on the impact of Cl doping on the potassium-ion diffusion rate in the cubic phase K<sub>3</sub>SbS<sub>4</sub> using the DeePMD method. The doped material can achieve an ionic conductivity of 14.8 mS/cm at a temperature of 300 K. Thanks to the relatively fast calculation speed, we also evaluated the impact of sampling time and model size on the reproducibility of simulation results. The results show that a simulation of a 3400-atom system for 500 ps can ensure good reproducibility.
Molecular dynamics simulation has become an important tool for understanding the properties and mechanisms of solid-state electrolytes. However, the first-principles molecular dynamics simulation (AIMD) is slow in calculation because it needs to continuously solve the Schrödinger equation, and the atom system that can be simulated usually does not exceed 300 - 500 atoms. Due to insufficient sampling, the results of each simulation for the same system at the same temperature may vary, as has been shown in our previous article.<sub>1</sub>

This study focuses on the impact of Cl doping on the potassium-ion diffusion rate in the cubic phase K<sub>3</sub>SbS<sub>4</sub> using the DeePMD method. The doped material can achieve an ionic conductivity of 14.8 mS/cm at a temperature of 300 K. Thanks to the relatively fast calculation speed, we also evaluated the impact of sampling time and model size on the reproducibility of simulation results. The results show that a simulation of a 3400-atom system for 500 ps can ensure good reproducibility.

## Research Results

Expand All @@ -38,7 +40,7 @@ Further, we used DeePMD to conduct a systematic study of the system. The doping

*Figure 3: Influence of Doping on the Trajectory of Potassium Ions*

Finally, we introduced the Van Hove correlation function.2 It can be seen that for the undoped system (Figure 4a, c), the correlation function parts G<sub>s</sub>(t,r) of the same particles at different times and the correlation function parts G<sub>d</sub>(t,r) of different particles are relatively stable, which indicates that the particles do not migrate. In contrast, for the doped system, whether it is the disappearance of G<sub>s</sub>(t,r) in r = 1 Å or the gradual accumulation of G<sub>d</sub>(t,r) with time, both show the typical characteristics of highly correlated jumps of particles.
Finally, we introduced the Van Hove correlation function.<sub>2</sub> It can be seen that for the undoped system (Figure 4a, c), the correlation function parts G<sub>s</sub>(t,r) of the same particles at different times and the correlation function parts G<sub>d</sub>(t,r) of different particles are relatively stable, which indicates that the particles do not migrate. In contrast, for the doped system, whether it is the disappearance of G<sub>s</sub>(t,r) in r = 1 Å or the gradual accumulation of G<sub>d</sub>(t,r) with time, both show the typical characteristics of highly correlated jumps of particles.

<center><img src=https://dp-public.oss-cn-beijing.aliyuncs.com/community/Blog%20Files/DeePMD_13_12_2024/figure4.png pic_center width="100%" height="100%" /></center>

Expand All @@ -54,6 +56,6 @@ The interface study of solid-state electrolytes is currently a hot and difficult

## References

Zhang, R.; Xu, S.; Wang, L.; Wang, C.; Zhou, Y.; Lü, Z.; Li, W.; Xu, D.; Wang, S.; Yang, X., Theoretical Study on Ion Diffusion Mechanism in W-Doped K3SbS4 as Solid-State Electrolyte for K-Ion Batteries. Inorganic Chemistry 2024, 63 (15), 6743-6751.
1. Zhang, R.; Xu, S.; Wang, L.; Wang, C.; Zhou, Y.; Lü, Z.; Li, W.; Xu, D.; Wang, S.; Yang, X., Theoretical Study on Ion Diffusion Mechanism in W-Doped K3SbS4 as Solid-State Electrolyte for K-Ion Batteries. Inorganic Chemistry 2024, 63 (15), 6743-6751.

Van Hove, L., Correlations in Space and Time and Born Approximation Scattering in Systems of Interacting Partitives. Phys. Rev. 1954, 95 (1), 249-262.
2. Van Hove, L., Correlations in Space and Time and Born Approximation Scattering in Systems of Interacting Partitives. Phys. Rev. 1954, 95 (1), 249-262.
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