Dolgonos Grygoriy A, Peslherbe Gilles H
Centre for Research in Molecular Modeling (CERMM) and Department of Chemistry & Biochemistry, Concordia University, Montréal, Québec, Canada.
J Mol Model. 2007 Sep;13(9):981-6. doi: 10.1007/s00894-007-0216-5. Epub 2007 Jun 23.
The C2 fragmentation energies of the most stable isolated-pentagon-rule (IPR) isomers of the C80 and C82 fullerenes were evaluated with second-order Møller-Plesset (MP2) theory, density-functional theory (DFT) and the semiempirical self-consistent charge density-functional tight-binding (SCC-DFTB) method. Zero-point energy, ionization energy and empirical C2 corrections were included in the calculation of fragmentation energies for comparison with experimental C2 fragmentation energies of the fullerene cations. In the case of the most probable Stone-Wales pathway of C2 fragmentation of C80, the calculated [Formula: see text] agree well with experimental data, whereas in the case of C(82) fragmentation, the calculated [Formula: see text] exceed by up to 1.2 eV the experimental ones, which suggests that other IPR isomers may be present in sufficient amounts in experimental samples. Computer-intensive MP2 calculations and DFT calculations with larger basis sets do not yield much improved C2 fragmentation energies, compared to those reported earlier with B3LYP/3-21G. On the other hand, semiempirical approaches such as SCC-DFTB, which are orders of magnitude less intensive, yield satisfactory fragmentation energies for higher fullerenes and may become a method of choice for routine calculations of fullerenes and carbon nanotubes.
利用二阶莫雷尔-普列斯特定理（MP2）、密度泛函理论（DFT）和半经验自洽电荷密度泛函紧束缚（SCC-DFTB）方法，对C80和C82富勒烯最稳定的孤立五边形规则（IPR）异构体的C2裂解能进行了评估。在裂解能的计算中纳入了零点能、电离能和经验性C2校正，以便与富勒烯阳离子的实验C2裂解能进行比较。对于C80最可能的C2裂解的斯通-威尔士途径，计算得到的[公式：见原文]与实验数据吻合良好，而对于C82裂解的情况，计算得到的[公式：见原文]比实验值高出多达1.2 eV，这表明在实验样品中可能存在足够数量的其他IPR异构体。与早期用B3LYP/3-21G报道的结果相比，计算量较大的MP2计算和使用更大基组的DFT计算并没有使C2裂解能有很大改善。另一方面，诸如SCC-DFTB这样的半经验方法，计算强度要低几个数量级，对于更高的富勒烯能给出令人满意的裂解能，可能会成为富勒烯和碳纳米管常规计算的首选方法。
