Get periodic boundary condition of the DCD

TCL script to get periodic boundary condition of the system.

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## TCL script to get periodic boundary condition of the system
## Kevin Apr 2014
## Usage: vmd -dispdev text -e getpbc.tcl
## Input: pdb dcd
## Output: xyz
## Units:
## Notes: 
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set filename "unsym"
set dir "/nfs/disk3/cchan2242/BAR-PH/raw/unsym/"
mol new $dir/ionized.pdb type pdb waitfor all
animate delete all
mol addfile $dir/NPT-11.dcd type dcd waitfor all

set frames [ molinfo top get numframes ]

set outpbc [open $filename+pbc.xyz w]

for { set t 0 } { $t < $frames } { incr t } {
  set temp [pbc get -first $t -last $t -molid top]

  set xlength [lindex $temp 0 0]
  set ylength [lindex $temp 0 1]
  set zlength [lindex $temp 0 2]

  puts $outpbc "$xlength $ylength $zlength"
}
close $outpbc
quit