Alternatively, you can use ESPiso_eV.bat along with ESPiso_eV.txt in "examples\drawESP\" instead of ESPiso.bat along with ESPiso.txt. In this case, the grid data of ESP exported by Multiwfn will be in eV, so you can input the color scale in VMD in a much larger magnitude.

Alternatively, you can use VMD command to directly set the color scale. In ESPiso.vmd you can find the following two lines, you can change the values and run them in VMD console window manually.

set colorlow -0.03
set colorhigh 0.03

I exported surfanalysis.pdb, geometry.pdb, and mapfunc.cub from Multiwfn (from options 2, 5, 13).
I load them in VMD manually, but I have problems:
I can set isovalue to 0.001 or 0.002 in VMD

But the color scale range (e.g., -0.002 to 0.002) resets to 0 unless I use larger values like 0.01

The isosurface appears:

In one color only

Or with overlapping red/blue

Or broken with holes unless isovalue is ≥ 0.01

I tried different grid spacings in Multiwfn (0.2, 0.15, 0.1) — no success. Also tested VMD versions 1.9.1, 1.9.3, and 1.9.4.
Help Needed:
How to fix the color scale reset issue?

How to get a closed transparent red–blue surface at isovalue 0.001?

Is there a custom VMD version with iso, pt, esp commands like in the video?

Any working .tcl script or .vmd template for this setup?

Thanks in advance!