Planar-to-tubular structural transition in boron clusters: B 20 as the embryo of single-walled boron nanotubes

Kiran et al. 10.1073/pnas.0408132102.

Supporting Information

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Supporting Figure 4
Supporting Figure 5
Supporting Table 2

Supporting Figure 4

Fig. 4. Photoelectron spectra of B₂₀^- at different source conditions to demonstrate the significant temperature effects on the photoelectron spectra (1-3). (Upper) Cold clusters. (Lower) Hot clusters. Note that hot clusters result in broad spectra, smearing out the spectral features even under high instrumental resolution (1).

1. Wang, L. S. & Li, X. (2000) in Clusters and Nanostructure Interfaces, eds. Jena, P., Khanna, S. N. & Rao, B. K. (World Scientific, Teaneck, NJ), pp. 293–300.

2. Akola, J., Manninen, M., Hakkinen, H., Landman, U., Li, X. & Wang, L. S. (1999) Phys. Rev. B 60, R11297–R11300.

3. Zhai, H. J., Wang, L. S., Alexandrova, A. N. & Boldyrev, A. I. (2002) J. Chem. Phys. 117, 7917–7924.

Supporting Figure 5

Fig. 5. Selected structures of B₂₀^- (B₂₀) along with their relative energies (numbers in parentheses are the relative energies for neutral B₂₀) and adiabatic detachment energies (ADE) in boldface. All calculations were done at the B3LYP/6-311+G* level by using NWCHEM (1). All energies are given in eV.

1. High Performance Computational Chemistry Group (2002) NWCHEM, A Computational Chemistry Package for Parallel Computers (Pacific Northwest National Laboratory, Richland, WA), Version 4.6.

Table 2. Relative energies (RE), bond energy per atom (B.E./atom), and HOMO–LUMO gaps (E_HL for the virtual LUMO), all in eV, calculated at B3LYP/6-311+G* level for the four lowest-energy isomers of B_20- and B₂₀ clusters (see Fig. 2)

Structure	RE (anion)	RE (neutral)	B.E./atom (neutral)	E_HL (neutral)
1	0.00	0.00	4.78	2.49
2	0.13	0.99	4.73	2.19
3	0.16	0.83	4.74	2.46
4	0.28	0.99	4.73	2.51