Hi there,

I used the following script to merge two trajectories into one but nothing is written in the merged .dcd

! Read topology and parameter files
stream toppar.str

read the psf and coordinate file
read psf card name complex-neutralized.psf
read coor card name complex-equil.crd



!Read input trajectories
open read unit 40 file name complex-equil-1.dcd
open read unit 41 file name complex-equil-2.dcd

!Write output coordinate
open write unit 60 file name ret_complex-merge.dcd

! New, merged trajectory
merge coor first 40 nunit 2 begin 0 output 60 skip 1000- ! one frame/ps is all we need


Is there anything that I need to add or changed?
Thanks

The BEGIN 0 seems a bit odd; were the input .dcd files generated with CHARMM?

The output log file may have some clues.