title: Self-Trapping of Charge Carriers in Semiconducting Carbon Nanotubes: Structural Analysis.
abstract: The spatial extent of charged electronic states in semiconducting carbon nanotubes with indices (6,5) and (7,6) was evaluated using density functional theory. It was observed that electrons and holes self-trap along the nanotube axis on length scales of about 4 and 8 nm, respectively, which localize cations and anions on comparable length scales. Self-trapping is accompanied by local structural distortions showing periodic bond-length alternation. The average lengthening (shortening) of the bonds for anions (cations) is expected to shift the G-mode frequency to lower (higher) values. The smaller-diameter nanotube has reduced structural relaxation due to higher carbon-carbon bond strain. The reorganization energy due to charge-induced deformations in both nanotubes is found to be in the 30-60 meV range. Our results represent the first theoretical simulation of self-trapping of charge carriers in semiconducting nanotubes, and agree with available experimental data.
authors.affiliation: Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Lyudmyla
authors.initials: L
authors.lastname: Adamska
authors.affiliation: Department of Chemistry and Biochemistry, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: George V
authors.initials: GV
authors.lastname: Nazin
authors.affiliation: Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Doorn
authors.affiliation: Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.|Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Sergei
authors.initials: S
authors.lastname: Tretiak
keywords: carbon nanotubes; density functional theory; electron−phonon interaction