Shao, Nan and Gao, Yi and Zeng, Xiao Cheng (2007) Search for lowest-energy fullerenes 2: C-38 to C-80 and C-112 to C-120. JOURNAL OF PHYSICAL CHEMISTRY C, 111 (48). pp. 17671-17677.
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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp0701082
An efficient computational approach that combines semiempirical density-functional based.tight-binding method (DFTB) for geometry optimization and density-functional theory for single-point energy calculation is employed to search for the lowest-energy structures of higher fullerenes C-110 to C-120. In addition, a systematic study of low-lying structures of lower fullerenes C-38 to C-80 is undertaken. For the latter study, the targeted isomers amount to 131 164, including 17 IPR (isolated pentagon rule) isomers and all non-IPR isomers. Non-IPR isomers dominate the low-lying population of C-72 but are gradually phased out of the low-lying population when the fullerene size increases toward C-80. An unexpected manner of pentagonal adjacency was observed, that is, for fullerenes containing an adjacent-pentagon chain with less than five pentagons, the longer chain incurs less energy penalty than the shorter chain when the top-two lowest-energy fullerene cages (for all C-38-C-70) have the same number of adjacent pentagons-For higher fullerenes C-112 to C-120, a full set of total 32 795 IPR isomers were optimized using the DFTB method. An energy cutoff value of 6.3 kcal/mol was used to collect low-lying candidate isomers for the second-stage single-point energy calculation at the DFT level. Multiple candidates for the lowest-energy structure were identified for C-112, C-118, and C120. Among them, C-112:3299 and C-118:7308 exhibit a large HOMO-LUMO gap. For C-116, a sole candidate for the lowest-energy structure was identified, namely, C-116:6061 which has a high T-h symmetry and a large HOMO-LUMO gap and is 12.5 kcal/mol lower in energy than the second lowest-energy isomer. Thus, C-116: 6061 is most likely to be isolated first in the laboratory among the five large fullerenes. C-13 NMR spectra of the ten lowest-energy isomers Of C-112 to C-120 were calculated for comparison with the experiment.
|Subjects:||Physical Science > Nano objects|
Material Science > Nanochemistry
|Deposited By:||Farnush Anwar|
|Deposited On:||13 Jan 2009 13:23|
|Last Modified:||26 Jan 2009 16:36|
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