In addition to the bonded interactions between atoms described above, force fields also contain non-bonded interactions. Non-bonded interactions act between atoms in the same molecule and those in other molecules. Force fields usually divide non-bonded interactions into two: electrostatic interactions and Van der Waals interactions.
The electrostatic interaction arises due to the unequal distribution of charge in a molecule. A simple example is the hydrogen fluoride (HF) molecule, where the hydrogen atom is slightly positive and the fluorine is slightly negative. Within the force field framework this uneven distribution of charge can be modelled by placing point charges at each of the atomic sites. Due to charge conservation for a neutral molecule these sum to zero. Thus in the previous example we would have $q_F=-q_H$. The interaction between these point charges is generally modelled by a Coulomb potential