From: Diego Gomes (
Date: Mon Jan 29 2024 - 10:17:37 CST

I'll look into the issue, which looks like a Windows-only issue, and I bet
it is related to a 2Gb file size limitation.

Can you please share which Windows version you are using? Also, did you try
using NAMD 2.14 instead of 2.13 ?


My bet is that 1M is less than 2Gb, and 4M is > 2Gb.

On Fri, Jan 26, 2024 at 8:18 AM Alexei Rossokhin <> wrote:

> Dear VMD users,
> recently installed VMD for WIN64 version 1.9.4a53 (June 29, 2021). It
> reads my large DCD files correctly. I can visualize trajectories
> assembled from individual files with a total of over 4M iterations for a
> system with 161778 atoms.
> However, when I use the NAMDenergy plugin, I can only calculate energy for
> runs with 1M iterations. If I upload more, I will get an error. In the
> log file:
> dcdplugin) Could not access file 'namd-temp.dcd'.
> TCL: coorfile: Error opening file namd-temp.dcd
> FATAL ERROR: coorfile: Error opening file namd-temp.dcd
> while executing
> "coorfile open dcd namd-temp.dcd"
> (file "namd-temp.namd" line 36)
> It appears when the following command runs
> F:/NAMD_2.13_Win64-multicore/namd2.exe namd-temp.namd
> If anyone has encountered this problem before, I would appreciate any
> advice.
> Alexey

Diego Enry B. Gomes, PhD
Department of Physics at Auburn University &
NIH Center for Macromolecular Modeling and Visualization
Leach Science Center - Ste. 3182 - Auburn, AL