Internal stresses in molecules

In this paper a generalized concept of stresses in molecular systems is presented. The stress tensor in the 3-D space of a molecule, defined in terms of internal fields arising from its nuclear and electronic distributions, has components with forms reminiscent of Maxwell's stress tensor for classical electromagnetic fields. As an illustrative example, the stress tensor has been calculated for the 1s, 2s and 2px states of the hydrogen atom. The physical significance of the various components of the stress tensor is also examined. The stress concept is likely to yield considerable insight into molecular phenomena such as chemical binding, molecular geometry, chemical reactivity and transferability of fragment properties from one molecule to another.