Unit of Electrostatic Potential (ESP) Analysis in IQmol

Questions
#1

I used ESP_GRID and obtained values as shown below.

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Then, I created a cube file and drew the figure using those values. However, I’m not sure if the values are in eV (electron volts) or dimensionless units, as I’ve seen similar figures but couldn’t find specific information on how to interpret the values. Can you provide some guidance on how to determine the units and understand the meaning of the obtained values? I have to do ESP analysis.

#2

The values in your cube file are in atomic units, could be converted to eV and if IQmol labels them in eV, I have no reason to believe this is wrong. If you want to verify, you can load the cube file using VMD and plot your own isosurface in atomic units.