which one is better, vacf or ave/correlate of velocity

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1

Respected authority,
Please clarify my doubt regarding which way is better to find velocity auto correlation, using vacf or ave/correlate?

Let say I have only 1 atom in my group.

For given ‘delta’ (time) vacf calculates only once the value of coefficient but ave/correlate calculates the same value by carrying out average over several samples having same delta gap.

This gives me the feeling that ave/correlate is better than vacf.

Please rectify me , if I am wrong at any point.
Thankfully.

2

Yes, that is correct. fix ave/correlate is a newer, more general method in LAMMPS that allows an arbitrary number of prior reference values to be compared to the current value. compute vacf only uses the initial value as reference.

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3

Thank you for the reply.