In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) or compressive (contractile) force is called strain energy.
For linearly elastic materials, strain energy is: where σ is stress, ε is strain, V is volume, and E is Young's modulus: In a molecule, strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction.
[1] The external work done on an elastic member in causing it to distort from its unstressed state is transformed into strain energy which is a form of potential energy.
For example, the heat of combustion of cyclopropane (696 kJ/mol) is higher than that of propane (657 kJ/mol) for each additional CH2 unit.
Compounds with unusually large strain energy include tetrahedranes, propellanes, cubane-type clusters, fenestranes and cyclophanes.