  Chirality-selected single-walled carbon nanotubes (SWCNTs) ensure a great
potential of building ~1 nm sized electronics. However, the reliable method for
chirality-selected SWCNT is still pending. Here we present a theoretical study
on the SWCNT's chirality assignment and control during the catalytic growth.
This study reveals that the chirality of a SWCNT is determined by the kinetic
incorporation of the pentagon formation during SWCNT nucleation. Therefore,
chirality is randomly assigned on a liquid catalyst surface. Furthermore, based
on the understanding, two potential methods of synthesizing chirality-selected
SWCNTs are proposed: i) by using Ta, W, Re, Os, or their alloys as solid
catalysts, and ii) by changing the SWCNT's chirality frequently during the
growth.
