Thank you very much for your reply and clearing my doubts about ACF length. By referring to several papers, now I know that reaching ACF to zero implies having independent samples after 300 ns. Previously, I was confused with one of the replies in Autocorrelation function of radius of gyration - #5 by MOH4
By calculating the block average with error estimation (gmx analyze with -ee option), can we show the convergence of an MD system (observing a plateau in error estimate vs block size graph) ? For the calculation of the block average, do we need to have independent samples? Appreciate it if you could comment on this.