From: Lothar Esser (
Date: Fri Nov 20 2020 - 12:30:57 CST


   because of the excellent visual representation of surfaces when ambient
occlusion is used, I am planning to render a surface with electrostatic
potential in Tachyon (in-memory). However, tachyon only produces black and
white surfaces. That is in contrast to colored surfaces say colored by atom
types. So this is surprising.
I am using 1.9.4a48 on CentOS7.

Also, I noticed that whenever I use ambient occlusion, regardless of
whether I turn on or off Shadows in Graphic options, it renders the scene
*with* shadows. Previous versions of vmd did not do that as far as I

A smaller side issue is that vmd does not execute APBS even though it is in
the path. After running APBS (local) it displays immediately: APBSRun:
output files missing or unreadable.
Obviously it does not even try to execute it. However the file can
be run on the commandline with apbs and the pot.dx file copied to
the working directory.
Not that important but, if someone knows whether this is a permission issue
or something else, I would like to know how to fix it.

The major issue for me is that Tachyon does not render surfaces colored by
(APBS) electrostatic potential and to a much lesser degree the problem that
shadows are always on even when they are turned off.

Any advice is appreciated.