Optical saturation driven by exciton confinement in molecular chains: a time-dependent density-functional theory approach.
We identify excitonic confinement in one-dimensional molecular chains (i.e., polyacetylene and H2) as the main driving force for the saturation of the chain polarizability as a function of the number of molecular units. This conclusion is based on first principles time-dependent density-functional theory calculations using a recently developed exchange-correlation kernel that accounts for excitonic effects. The failure of simple local and semilocal functionals is shown to be linked to the lack of memory effects, spatial ultranonlocality, and self-interaction corrections. These effects get smaller as the gap reduces, in which case such simple approximations do perform better.
National Center on nanoStructures and Biosystems at Surfaces (S3) of INFM-CNR, Via Campi 231/A, 41100 Modena, Italy.
Daniele
D
Varsano
Andrea
A
Marini
Angel
A
Rubio
D006859:Hydrogen / Q000737:chemistry*; D008956:Models, Chemical; D053279:Polyynes / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry; D013816:Thermodynamics
D011506:Proteins; D053279:Polyynes; D006859:Hydrogen