The electrostatic potential at a point around a molecule is usually defined as the work required to move a unit of positive charge from infinity to this point. (Simply speaking, if other factors are not considered, when the electrostatic potential of a certain point in the space around the molecule is positive, it means that this point is repulsive to positive charges; on the contrary, if the electrostatic potential of a certain point is negative, it means This point is attractive to positive charges). Electrostatic Potential Mapping https://www.computabio.com/electrostatic-potential-mapping-service-on-molecular-surface.html