Eg. Galpern et al., CARBON NANOTUBES WITH METAL INSIDE - ELECTRON-STRUCTURE OF TUBELENES [LI-AT-C24]N AND [K-AT-C36]N, Chemical physics letters, 214(3-4), 1993, pp. 345-348
Electron energy spectra have been computed of tube-like carbon cluster
s [C24]n and [C36]n, intra-doped With Li and K, respectively, by the e
xpanded Huckel method. It is shown that the nanotubes change from semi
-metal character (undoped) to metal (alkali-metal-doped carbon tubes).