Communication: Modular path integral: Quantum dynamics via sequential necklace linking.

It is shown that dynamical properties of extended systems (spin arrays, large organic molecules, or molecular aggregates) characterized primarily by local potential interactions (bond stretching, bending, and torsional interactions) can be obtained efficiently from fully quantum mechanical path integral calculations through sequential linking of the quantum paths or path integral necklaces corresponding to adjacent groups of atoms, which comprise the "modules." The scheme is applicable to complex chemical systems and is characterized by linear or sublinear scaling with system size. It is ideally suited to studies of vibrational energy flow and heat transport in long molecules (which may also be attached to solids), as well as simulations of exciton-vibration dynamics in molecular aggregates.