From: soroush ziaei (
Date: Thu Jan 17 2019 - 06:57:21 CST

because of some problems and many features that have been changed in the newer version, My suggestion is to work with Ubuntu 16.04 LTS instead of 2018 version.
By the way, I have loaded these files a few minutes ago into fep plugin of VMD and easily plotted these values with xmgrace. I think your problem is related to loading file!
Please load <aqua-forward-on.fepout> & <aqua-backward-on.fepout>.
I hope to done.


Sent from Mail for Windows 10

From: surya narayanan chandrasekaran
Sent: Wednesday, January 16, 2019 4:58 PM
Subject: vmd-l: FEP tutorial plot error


    I was doing alchemical FEP tutorial. After doing the forward and backward step i was trying to analyse the .fepout in the vmd plugin and got the below error. My computer is Linux based (ubuntu 18) and i have xmgrace and gnuplot installed in it.

option i selected in the plugin:
GRM-Charlier: 0
disp (on) for unix ststems only
forward and backward .fepout file loaded

Error: missing close-bracket

missing close-bracket
    while executing
"set lambda1 [format "%8.4f"    [lindex $::ParseFEP::fwd_lambda $index]
                                        set lambda2 [format "%8.4f"    [lindex ..."
    invoked from within
"if { [file exists [format "file%d.dat" $file_index] ] }  {
                                        set lambda1 [format "%8.4f"    [lindex $::ParseFEP:..."
    (procedure "::ParseFEP::fepdisp_unix" line 321)
    invoked from within
"::ParseFEP::fepdisp_unix "
    (procedure "namdparse" line 47)
    invoked from within
    (in namespace inscope "::ParseFEP" script line 16)
    invoked from within
"::namespace inscope ::ParseFEP {
         if { [string length $::ParseFEP::fepofile] < 1 } {
            tk_dialog .errmsg {NamdPlot Error} "No ..."
    invoked from within
".parseFEP.runbutton invoke"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 [list $w invoke]"
    (procedure "tk::ButtonUp" line 22)
    invoked from within
"tk::ButtonUp .parseFEP.runbutton"
    (command bound to event)

Warm regards,
Dr. Suryanarayanan C