Coherent phonons in excited-state carbon nanotubes: A simulation by tight-binding molecular dynamics

摘要: Abstract We have made tight-binding molecular dynamics simulations on the coherent phonons induced by electron–phonon coupling in low energy optically excited states of single-walled carbon nanotubes (SWCNTs) with different diameters and chiralities. It is found that: (1) SWCNT’s radial breathing mode (RBM) longitudinal optical (LO) are easily due to their direct band electrons, which then causes gap oscillations same frequencies as those RBM LO modes. (2) Excitation exhibits an interesting family-behavior. For example, for family-II tubes, such (11,0), (17,0) (10,5) tubes mod(n−m,3)=2, amplitude first E11 transition smaller than that second E22 one, while opposite situation appears a family-I tube its mod(n−m,3)=1, e.g., (10,0) (16,0) tubes. (3) Transverse (TO) modes cannot be zigzag (11,0) but can chiral tube. The above obtained results good agreement experimental observations.