Coherence of Particles and Holes in Excitation Migration: A Density-matrix Analysis

Document Type

Conference Presentation



Conference Title

American Chemical Society Meeting


American Chemical Society (ACS)


Denver, CO

Conference Dates

August 28-September 1, 2011

Date of Presentation



In our analysis of the dynamic one-electron difference-density matrices arising from time-dependent many-body states, we have observed two very distinct modes for the migration of an excitation through a system. In one case, coherences in the density matrix give rise to single particle and hole states that appear to migrate as independent units. Though interacting, they are independent in the sense that the single-electron state that describes an individual particle or hole is everywhere entangled with the same state of the electrons that have been integrated/traced out. These pseudo-wavefunctions carry nontrivial phase information (nonzero momentum), which is consistent with their observed direction of travel. The other case is dominated by a transition that can be thought of as the closing of a particle--hole pair in one location, entangled with the opening of such a pair in another location. In this case, the spatially-dependent phase of a given particle or hole state lies very near the real axis, reminiscent of time-independent molecular orbitals.

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