American Journal of Physics
If two bound nonrelativistic quantum particles are each subject to a nonlinear external potential, their Schrödinger equation does not separate in relative and center‐of‐mass coordinates. For this case, the details of internal state of the composite affect its center‐of‐mass properties. The extent of this internal state influence is examined for an exactly soluble one‐dimensional model system.
Lock, James A., "Center-of-Mass Properties of Composite Systems Subject to Non-Linear External Interactions" (1983). Physics Faculty Publications. 15.
Lock, James A. "Center-of-Mass Properties of Composite Systems Subject to Non-Linear External Interactions." American Journal of Physics 51 (1983): 717-721.
Copyright 1983 American Association of Physics Teachers. The article appeared in American Journal of Physics 51 (1983): 717-721 and may be found at http://aapt.scitation.org/doi/abs/10.1119/1.13153