Nanoporous carbon structures based on C${}_{20}$

In this paper, we present computational results for C${}_{20}$ based solids. We propose structures that are shown to be energetically more favorable and stable than previously suggested structures. The so-called quasigraphite phase and base-centered-monoclinic type structures are found to be the energetically most favorable. The molecular-dynamics stability of suggested structures was studied via constant-temperature and constant-pressure techniques and by examining phonon dispersion curves. All the predicted structures demonstrate high stability with respect to temperature and external load. By changing the geometry, the electronic properties can be varied from metallic to insulating.

Figure 1

Geometry of C${}_{20}$ bcm-type, qgp, and C${}_{22}$-fcc structures.

Figure 2

Geometry of C${}_{20}$ sc-type, bcc, and hcp structures.

Figure 3

Band structure plots for energetically most favorable structures: (a) qgp, (b) bcc, (c) fcc-22, (d) bcm${}_{\mathrm{open}}$, (e) sc, and (f) bcm${}_{\mathrm{closed}}$

Figure 4

Calculated dispersion relations for (a) fcc-22 (b) bcm${}_{\mathrm{closed}}$, (c) bcm${}_{\mathrm{open}}$, (d) qgp (e) bcc, and (f) sc${}_{\mathrm{open}}$ structures.

Figure 5

Calculated Raman spectra for (a) qgp, (b) bcc, (c) fcc-22, (d) bcm${}_{\mathrm{closed}}$, and (e) sc${}_{\mathrm{open}}$ structures.