From: George Mogami (
Date: Wed Feb 05 2020 - 23:00:10 CST

Dear John,
Thank you for your reply. Your advice was to the point.
I am using MobaXterm as Xserver with SSH terminal,
which is useful because X11-forwarding and DISPLAY settings are constructed automatically.
However, it means we can not know the internal settings except for the DISPLAY environment variable (localhost:10.0).
Then, I tried to stop Xserver of MobaXterm and start Xming,
and set the DISPLAY environment variable as (remote PC address),
and VMD was launched with no error.

If I ran "wish" (not wishx) using MobaXterm X-forwarding,
grey small window appeared and % was displayed in prompt with no error.
Although VMD became available, I wondered why only VMD Tk got failure.
In addition, using the same MobaXterm X-forwarding environment in another centos machine,
I confirmed VMD was launched with no error.
So, I think it's hard to isolate the problem.
Anyway, since this isn't an issue with VMD itself, my immediate problem was tentatively solved.
I would appreciate If you could give me a hint concerning the issue.
Thanks in advance.

Best regards,

On 2020/02/06 6:04, John Stone wrote:
> Hi,
> This isn't really an issue with VMD itself, but rather the X server
> and socket tunneling you're using. It seems that there's some sort
> of problem with the SSH tunnel you're using to forward your
> X server connection, which is why Tk is complaining about being unable
> to connect to the display "localhost:10.0".
> Your VMD seems to have successfully connected to a GLX X11 server
> back-end that identifies itself as "Software Rasterizer", but things
> appear to fail after that when Tk begins trying to initialize.
> Are you wable to run the "wishx" Tk shell on this arrangement without
> encountering that error?
> What do you have your DISPLAY environment variable set to prior to
> launching VMD?
> Best regards,
> John Stone
> On Wed, Feb 05, 2020 at 10:44:13AM +0900, George Mogami wrote:
>> Dear all,
>> I have used VMD installed in centos 6.8 from SSH connected PC.
>> Some time ago, VMD became not available using X forwarding.
>> Following is the log of VMD start:
>> $ vmd
>> Info) VMD for LINUXAMD64, version 1.9.2 (December 29, 2014)
>> Info)
>> Info) Email questions and bug reports to
>> Info) Please include this reference in published work using VMD:
>> Info)    Humphrey, W., Dalke, A. and Schulten, K., `VMD - Visual
>> Info)    Molecular Dynamics', J. Molec. Graphics 1996, 14.1, 33-38.
>> Info) -------------------------------------------------------------
>> Info) Multithreading available, 28 CPUs detected.
>> Info) Free system memory: 127916MB (99%)
>> Info) Creating CUDA device pool and initializing hardware...
>> Info) Detected 1 available CUDA accelerator:
>> Info) [0] GeForce GT 710      1 SM_3.5 @ 0.95 GHz,  980MB RAM, AE1, ZCP
>> Warning) Detected X11 'Composite' extension: if incorrect display occurs
>> Warning) try disabling this X server option.  Most OpenGL drivers
>> Warning) disable stereoscopic display when 'Composite' is enabled.
>> Info) OpenGL renderer: Software Rasterizer
>> Info)   Features: STENCIL MDE MTX NPOT PP PS
>> Info)   GLSL rendering mode is NOT available.
>> Info)   Textures: 2-D (16384x16384), 3-D (512x512x512), Multitexture (8)
>> MobaXterm X11 proxy: unable to connect to forwarded X server: Network error: Software caused connection abort
>> ERROR) Tk startup error: couldn't connect to display "localhost:10.0"
>> X I/O error
>> If other process such as "xeyes" and "glxgears", I can display them normally.
>> In text mode, "$ vmd -dispdev text", that works well.
>> When I login centos workstation directly and startx, I can use VMD normally.
>> Then, a problem seems to be around X forwarding setting.
>> I tried uninstall and reinstall VMD or install of another version of VMD(1.9.3) in another directory.
>> However, the same error occurred as above.
>> How can I fix the issue?
>> Thanks in advance.
>> Best regards,
>> George