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Abstract
We approach the problem of predicting excitation energies of diverse, larger (5–6 carbons)
carbonyl species central to earth’s tropospheric
chemistry. Triples contributions are needed
for the vertical excitation energy (Evert), while
EOM-CCSD//TD-DFT calculations provide acceptable estimates for the S1 relaxation energy (Erelax), and (TD-)DFT suffices for the
S0 → S1 zero-point vibration energy correction
(∆EZPVE).
Perturbative triples corrections deliver Evert
values close in accuracy to full iterative triples
EOM-CC calculations. The error between EOM-CCSD and triples-corrected E
vert values appears
to be systematic and can be accounted for with
scaling factors. However, saturated and α,β-unsaturated carbonyls must be treated separately. Double-hybrid S0 minima can be used to
calculate Evert with negligible loss in accuracy,
relegating the O(N5) expense of CCSD to only
single-point energy and excitation calculations.
This affordable protocol can be applied to all
volatile carbonyl species.
E0−0 predictions do overestimate measured
values by ∼8 kJ/mol due to a lack of triples
contribution in E
relax, but this overestimation
is systematic and the mean unsigned error is
within 4 kJ/mol once this is accounted for.
Supplementary materials
Title
SI Rowell Predicting Carbonyl Excitation Energies Efficiently Using EOM CC Trends
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Title
SI carbonyl 0-0 geoms SI
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