101 research outputs found
Time-Dependent Long-Range-Corrected Double-Hybrid Density Functionals with Spin-Component and Spin-Opposite Scaling: A Comprehensive Analysis of Singlet-Singlet and Singlet-Triplet Excitation Energies
No full textFollowing the work on spin-component and spin-opposite scaled (SCS/SOS) global double hybrids for singlet-singlet excitations by Schwabe and Goerigk [J. Chem. Theory Comput. 2017, 13, 4307-4323] and our own works on new long-range corrected (LC) double hybrids for singlet-singlet and singlet-triplet excitations [J. Chem. Theory Comput. 2019, 15, 4735- 4744; J. Chem. Phys. 2020, 153, 064106], we present new LC double hybrids with SCS/SOS that demonstrate further improvement over previously published results and methods. We introduce new unscaled and scaled versions of different global and LC double hybrids based on Becke88 or PBE exchange combined with LYP, PBE or P86 correlation. For singlet-singlet excitations, we cross-validate them on six benchmark sets that cover small to medium-sized chromophores with different excitation types (local valence, Rydberg, and charge transfer). For singlet-triplet excitations, we perform the cross-validation on three different benchmark sets following the same analysis as in our previous work in 2020. In total, 203 unique excitations are analyzed. Our results confirm and extend those of Schwabe and Goerigk regarding the superior performance of SCS and SOS variants compared to their unscaled parents by decreasing mean absolute deviations, root-mean-square deviations or error spans by more than half and bringing absolute mean deviations closer to zero. Our SCS/SOS variants show to be highly efficient and robust for the computation of vertical excitation energies, which even outperform specialized double hybrids that also contain an LC in their perturbative part. In particular, our new SCS/SOS-ωPBEPP86 and SCS/SOS-ωB88PP86 functionals are four of the most accurate and robust methods tested in this work and we fully recommend them for future applications. However, if the relevant SCS and SOS algorithms are not available to the user, we suggest ωPBEPP86 as the best unscaled method in this work
How do spin-scaled double hybrids designed for excitation energies perform for noncovalent excited-state interactions? An investigation on aromatic excimer models
No full textTime-dependent double hybrids with spin-component or spin-opposite scaling to their second-order perturbative correlation correction have demonstrated competitive robustness in the computation of electronic excitation energies. Some of the most robust are those recently published by our group [M. Casanova-Páez, L. Goerigk, J. Chem. Theory Comput. 2021, 20, 5165]. So far, the implementation of these functionals has not allowed correctly calculating their ground-state total energies. Herein, we define their correct spin-scaled ground-state energy expressions which enables us to test our methods on the noncovalent excited-state interaction energies of four aromatic excimers. A range of 22 double hybrids with and without spin scaling are compared to the reasonably accurate wavefunction reference from our previous work [A. C. Hancock, L. Goerigk, RSC Adv. 2023, 13, 35964]. The impact of spin scaling is highly dependent on the underlying functional expression, however, the smallest overall errors belong to spin-scaled functionals with range separation: SCS- and SOS-ωPBEPP86, and SCS-RSX-QIDH. We additionally determine parameters for DFT-D3(BJ)/D4 ground-state dispersion corrections of these functionals, which reduce errors in most cases. We highlight the necessity of dispersion corrections for even the most robust TD-DFT methods but also point out that ground-state based corrections are insufficient to completely capture dispersion effects for excited-state interaction energies
How Do DFT-DCP, DFT-NL, and DFT-D3 Compare for the Description of London-Dispersion Effects in Conformers and General Thermochemistry?
No full textThe dispersion-core-potential
corrected B3LYP-DCP method (Torres
and DiLabio J. Phys. Chem. Lett. 2012, 3, 1738) is for the first time thoroughly assessed
and compared with the B3LYP-NL (Hujo and Grimme J. Chem. Theory
Comput. 2011, 7, 3866) and
B3LYP-D3 (Grimme et al. J. Comput. Chem. 2011, 32, 1456) methods for a broad range of chemical
problems that particularly shed light on intramolecular London-dispersion
effects in conformers and general thermochemistry. The analysis is
based on a compilation of 473 reference cases, the majority of which
are taken from the GMTKN30 database (Goerigk and Grimme J.
Chem. Theory Comput. 2010, 6, 107; 2011, 7, 291). The results confirm
previous findings that B3LYP-DCP indeed predicts very good binding
energies for noncovalently bound complexes, particularly with small
basis sets. However, problems are identified for the description of
intramolecular effects in some conformers and chemical reactions,
for which B3LYP-DCP sometimes gives results similar or worse than
uncorrected B3LYP. Surprisingly large errors for total atomization
energies reveal an unwanted influence of the DCPs on the short-range
electronic structure of the investigated systems. However, a recently
modified carbon potential for B3LYP-DCP (DiLabio et al. Theor.
Chem. Acc. 2013, 132, 1389)
was additionally tested that seems to solve most of those problems
and provides improved results. An overall comparison between all tested
methods shows that B3LYP-NL is the most robust and accurate approach,
closely followed by B3LYP-D3. This is also true when small basis sets
of double-ζ quality are applied for which those methods have
not been parametrized. However, binding energies of noncovalently
bound complexes can be more strongly influenced by basis-set superposition-error
effects than for B3LYP-DCP. Finally, it is noted that the DFT-D3 and
DFT-NL schemes are readily applicable to a large range of chemical
elements and they are therefore particularly recommended for more
general applications
Exploring CPS-Extrapolated DLPNO–CCSD(T<sub>1</sub>) Reference Values for Benchmarking DFT Methods on Enzymatically Catalyzed Reactions
No full textDomain-based
local pair natural orbital coupled-cluster
singles
doubles with perturbative triples [DLPNO–CCSD(T)] is regularly
used to calculate reliable benchmark reference values at a computational
cost significantly lower than that of canonical CCSD(T). Recent work
has shown that even greater accuracy can be obtained at only a small
additional cost through extrapolation to the complete PNO space (CPS)
limit. Herein, we test two levels of CPS extrapolation, CPS(5,6),
which approximates the accuracy of standard TightPNO, and CPS(6,7),
which surpasses it, as benchmark values to test density functional
approximations (DFAs) on a small set of organic and transition-metal-dependent
enzyme active site models. Between the different reference levels
of theory, there are changes in the magnitudes of the absolute deviations
for all functionals, but these are small and there is minimal impact
on the relative rankings of the tested DFAs. The differences are more
significant for the metalloenzymes than the organic enzymes, so we
repeat the tests on our entire ENZYMES22 set of organic enzyme active
site models [Wappett, D. A.; Goerigk, L. J. Phys. Chem. A 2019, 123, 7057–7074] to confirm
that using the CPS extrapolations for the reference values has negligible
impact on the benchmarking outcomes. This means that we can particularly
recommend CPS(5,6) as an alternative to standard TightPNO settings
for calculating reference values, increasing the applicability of
DLPNO–CCSD(T) in benchmarking reaction energies and barrier
heights of larger models of organic enzymes. DLPNO–CCSD(T1)/CPS(6,7) energies for ENZYMES22 are finally presented as
updated reference values for the set, reflecting the recent improvements
in the method
Treating London-Dispersion Effects with the Latest Minnesota Density Functionals: Problems and Possible Solutions
No full textIt
is shown that the latest Minnesota density functionals (SOGGA11,
M11-L, N12, MN12-L, SOGGA11-X, M11, N12-SX, and MN12-SX) do not properly
describe London-dispersion interactions. Grimme’s DFT-D3 correction
can solve this problem partially; however, double-counting of medium-range
electron correlation can occur. For the related M06-L functional,
the alternative VV10 van der Waals kernel is tested, but it experiences
similar double-counting. Most functionals give unphysical dissociation
curves for the argon dimer, an indication for method-inherent problems,
and further investigation is recommended. These results are further
evidence that the London-dispersion problem in density functional
theory approximations is unlikely to be solved by mere empirical optimization
of functional parameters, unless the functionals contain components
that ensure the correct asymptotic long-range behavior. London dispersion
is ubiquitous, which is why the reported findings are not only important
for theoreticians but also a reminder to the general chemist to carefully
consider their choice of method before undertaking computational studies
The Nonlocal Kernel in van der Waals Density Functionals as an Additive Correction: An Extensive Analysis with Special Emphasis on the B97M‑V and ωB97M‑V Approaches
No full textThe
development of van der Waals density functional approximations
(vdW-DFAs) has gained considerable interest over the past decade.
While in a strictest sense, energy calculations with vdW-DFAs should
be carried out fully self-consistently, we demonstrate conclusively
for a total of 11 methods that such a strategy only increases the
computational time effort without having any significant effect on
energetic properties, electron densities, or orbital-energy differences.
The strategy to apply a nonlocal vdW-DFA kernel as an additive correction
to a fully converged conventional DFA result is therefore justified
and more efficient. As part of our study, we utilize the extensive
GMTKN55 database for general main-group thermochemistry, kinetics,
and noncovalent interactions [Phys. Chem. Chem. Phys. 2017, 19, 32184], which allows us
to analyze the very promising B97M-V [J. Chem. Phys. 2015, 142, 074111] and ωB97M-V
[J. Chem. Phys. 2016, 144, 214110] DFAs. We also present new DFT-D3(BJ) based counterparts
of these two methods and of ωB97X-V [J. Chem. Theory
Comput 2013, 9, 263], which
are faster variants with similar accuracy. Our study concludes with
updated recommendations for the general method user, based on our
current overview of 325 dispersion-corrected and -uncorrected DFA
variants analyzed for GMTKN55. vdW-DFAs are the best representatives
of the three highest rungs of Jacob’s Ladder, namely, B97M-V,
ωB97M-V, and DSD-PBEP86-NL
Double-Hybrid Density Functionals Provide a Balanced Description of Excited <sup>1</sup>L<sub>a</sub> and <sup>1</sup>L<sub>b</sub> States in Polycyclic Aromatic Hydrocarbons
No full textQuantum Chemical Investigation of Exciton Coupling: Super‐Molecular Calculations of a Merocyanine Dimer Aggregate
No full textDFT-D4 Counterparts of Leading Meta-GGA and Hybrid Density Functionals for Energetics and Geometries
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