Multiwfn forum

Dear Dr. Tian,
I've encountered an issue with creating an appropriate color bar scale for ESP in the VMD program.
Initially, the ESPiso.bat file was used for the 1.fch file to create the ESP1.cub + density.cub files. Then, the ESPiso.vmd script was utilized to generate the colored plot (as shown on the first screenshot). So, the result is as expected.

However, when I included the color bar via VMD, the value of the upper and lower limits was expressed in a.u. To convert it to more suitable "kcal/mol" values, I opened the ESPiso.vmd script that contains the following lines:

#Lower and upper limit of color scale of ESP (a.u.)
set colorlow -0.03
set colorhigh 0.03

and changed the respective values of the limits to -50 and 50 manually, as in the ESPpt.vmd script:

#Lower and upper limit of color scale of ESP (kcal/mol in most case)
set colorlow -50
set colorhigh 50

After this action, the gray transparent surface was generated. I understand that discoloration of the MEP surface is caused by changing upper and lower limits values while the resulting estimation of the limits is still expressed in a.u. (in other words, the program "sees" -50/50 a.u. instead of -50/50 kcal/mol).
I've analyzed your video tutorial on YouTube, where the following statement is present (on the second screenshot). But I don't clearly understand how to fix it manually (perhaps, it can be done using .bat files..) without external software like Photoshop.
So, I would highly appreciate your help.
Best regards,
Alex