We identify excitonic confinement in one-dimensional molecular chains (i.e., polyacetylene and H-2) 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.

Optical saturation driven by exciton confinement in molecular chains: A time-dependent density-functional theory approach

Varsano D;Marini A;
2008

Abstract

We identify excitonic confinement in one-dimensional molecular chains (i.e., polyacetylene and H-2) 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.
2008
INFM
CONJUGATED POLYMERS
ELECTRIC-FIELD
POLYACETYLENE
EXCITATIONS
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/124941
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