Auto correlation function for water molecules in a box

[vjramana]

I have simulated a box water molecules (1500 water molecules) using molecular dynamics method in NpT ensemble.

I got the time auto-correlation function (C(t) vs t, time) where its function line is parallel to x-axis. Which means the C(t) is zero.

I understand the water molecules are freely move around. Meaning they move randomly. There is no specific order or patters where the water molecules hold during its movement and get it lost after some time. And this is the reason the C(t) is zero.

I appreciate if anyone has better explanation for this result hope you can share so that I could expand my understanding.

Many thanks in advance.
Regards.

 

[eljose79]

Thank you for sharing your findings and observations from your simulation. The time auto-correlation function, or C(t), is a measure of the correlation between the positions of molecules at different points in time. In your case, the fact that the function line is parallel to the x-axis and C(t) is zero suggests that there is no correlation between the positions of the water molecules at different time points.

As you mentioned, this could be due to the random movement of the water molecules, which is expected in a molecular dynamics simulation. However, there could also be other factors at play that contribute to this result. For example, the size and shape of the simulation box, the temperature and pressure conditions, and the interactions between the water molecules could all affect the movement and behavior of the molecules.

To get a better understanding of your results, I would suggest further analyzing the trajectory of the water molecules and considering the various factors that could influence their movement. Additionally, you could compare your results to experimental data or other simulations to see if they align with previous findings.

I hope this helps expand your understanding and I look forward to hearing more about your research. Best of luck with your simulations!