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Performance of DFT for C60 Isomerization Energies: A Noticeable Exception to Jacob’s Ladder
journal contribution
posted on 2018-12-06, 00:00 authored by Amir Karton, Simone L. Waite, Alister J. PageThe
ability to accurately calculate relative energies of fullerenes
is important in many areas of computational nanotechnology. Because
of the large size of fullerenes, their relative energies cannot normally
be calculated by means of high-level ab initio procedures, and therefore,
density functional theory (DFT) represents a cost-effective alternative.
In an extensive benchmark study, we calculate the electronic energies
of eight C60 isomers by means of the high-level G4(MP2)
composite procedure. G4(MP2) isomerization energies span a wide range
between 307.5 and 1074.0 kJ mol–1. We use these
benchmark data to assess the performance of DFT, double-hybrid DFT
(DHDFT), and MP2-based ab initio methods. Surprisingly, functionals
from the second and third rungs of Jacob’s Ladder (i.e., GGA
and meta-GGA functionals) significantly and systematically outperform
hybrid and hybrid-meta-GGA functionals, which occupy higher rungs
of Jacob’s Ladder. In addition, DHDFT functionals do not offer
a substantial improvement over meta-GGA functionals, with respect
to isomerization energies. Overall, the best performing functionals
with mean absolute deviations (MADs) below 15.0 kJ mol–1 are (MADs given in parentheses) the GGA N12 (14.7); meta-GGAs M06-L
(10.6), M11-L (10.8), MN15-L (11.9), and TPSS-D3BJ (12.8); and the
DHDFT functionals B2T-PLYP (9.3), mPW2-PLYP (9.8), B2K-PLYP (12.1),
and B2GP-PLYP (12.3 kJ mol–1). In light of these
results, we recommend the use of meta-GGA functionals for the calculation
of fullerene isomerization energies. Finally, we show that inclusion
of very small percentages of exact Hartree–Fock exchange (3–5%)
slightly improves the performance of the GGA and meta-GGA functionals.
However, their performance rapidly deteriorates with the inclusion
of larger percentages of exact Hartree–Fock exchange.