We develop a theoretical model to account for the spin-induced atomic displacements in conjugated alternant hydrocarbons. It appears to be responsible for an enlargement of the distance between pairs of atoms separated by two atoms and located at the end of linear polyenes. It also correlates very well with the bond dissociation enthalpies for the cleavage of the C H bond as well as to the spin density at carbon atoms in both open and closed shell at graphene nanoflakes (GNFs). Finally, we have modified the Schrodinger equation to study the propagation of the spin-induced perturbations through the atoms of GNFs. (C) 2013 Elsevier B.V. All rights reserved.