Assessing long-range corrected functionals with physically-adjusted range-separated parameters for calculating the polarizability and the second hyperpolarizability of polydiacetylene and polybutatriene chains

The excited states of perylene-based dye aggregates were investigated with emphasis on the description of the potential energy surfaces for the intermolecular motion in a dimer, which are of importance for exciton trapping. The aim is to investigate the applicability of TDDFT and semiempirical methods. The longitudinal displacement of two p-stacked molecules against each other is used as model and the methods are benchmarked against SCS-CC2 and SCS-ADC(2). Furthermore a simple character analysis is applied. In the case of the perylene dimer, CAM-B3LYP and xB97XD provide accurate results. However, while CAM-B3LYP fails for the PBI (perylene bisimide) dimer the performance of xB97XD is highly dependent on the used monomer geometry due to close-lying diabatic states. A change in geometry changes the character of the excited states even qualitatively. The accuracy of several other long-range corrected functionals (LC-BLYP, LC-xPBE, xB97X) and the effect of empirically tuning the range-separation parameter of xB97XD are also presented for this interesting case. Furthermore, it is shown that the semiempirical method OM2 fails to provide a correct description of the excited states when the orbital overlap plays a significant role. This is attributed to the too contracted basis set.

show abstract

“…Gaussian uses a range separation parameter x50:47 bohr 21 , [55,56] while LC-xPBE [42] uses x50:4 bohr 21 .…”

Section: Tddftmentioning

confidence: 99%

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

Walter

Krämer

Engels

2016

Int J of Quantum Chemistry

View full text Add to dashboard Cite

show abstract

“…These difficulties stem from the fact that polarizabilities are second-order electronic properties and, as mentioned previously, will be extremely sensitive to exchange-correlation approximations in Kohn-Sham DFT methods (in particular, for computing γ). In a very recent paper by Champagne and co-workers, 16 To shed additional light on these previous conclusions, we present a new, detailed investigation using (1) non-empirically tuned range-separated functionals that include a portion of short-range HF exchange, and (2) an extensive analysis of broken-symmetry effects in rangeseparated functionals for calculating polarizabilities and second hyperpolarizabilies in PDA and PBT chains. In regards to the first point, previous work by our group 17 and others 18-21 has suggested that the inclusion of some short-range HF exchange does improve the accuracy of computed excited-state properties, and we demonstrate that this also enhances the accuracy of computed polarizabilities.…”

Section: Introductionmentioning

confidence: 98%

Polarizabilities of π-Conjugated Chains Revisited: Improved Results from Broken-Symmetry Range-Separated DFT and New CCSD(T) Benchmarks

Oviedo

Ilawe

Wong

2016

J. Chem. Theory Comput.

View full text Add to dashboard Cite

We present a detailed analysis of nonempirically tuned range-separated functionals, with both short- and long-range exchange, for calculating the static linear polarizability and second hyperpolarizabilities of various polydiacetylene (PDA) and polybutatriene (PBT) oligomers. Contrary to previous work on these systems, we find that the inclusion of some amount of short-range exchange does improve the accuracy of the computed polarizabilities and second hyperpolarizabilities. Most importantly, in contrast to prior studies on these oligomers, we find that the lowest-energy electronic states for PBT are not closed-shell singlets, and enhanced accuracy with range-separated DFT can be obtained by allowing the system to relax to a lower-energy broken-symmetry solution. Both the computed polarizabilities and second hyperpolarizabilities for PBT are significantly improved with these broken-symmetry solutions when compared to previously published and current benchmarks. In addition to these new analyses, we provide new large-scale CCSD(T) and explicitly correlated CCSD(T)-F12 benchmarks for the PDA and PBT systems, which comprise the most complete and accurate calculations of linear polarizabilities and second hyperpolarizabilities on these systems to date. These new CCSD(T) and CCSD(T)-F12 benchmarks confirm our DFT results and emphasize the importance of broken-symmetry effects when calculating polarizabilities and hyperpolarizabilties of π-conjugated chains.

show abstract

“…These RS functionals with default values of w consistently give less negative (higher lying) LUMO energies, more negative (lower lying) HOMO energies, high HOMO-LUMO gap and high vertical excitation energies of conjugated systems compared to experimental values [12,20]. Recently reported studies on optimizing w have aimed either satisfying the Koopmans' theorem [21][22][23] or reproducing high-level ab initio data [24][25][26][27][28]. The optimal values of w for range of conjugated systems are not well justified yet and the lack of these optimal values is responsible for the discrepancy between computed and experimental orbital energies.…”

Section: Introductionmentioning

confidence: 85%

Tuning range-separated DFT functionals for accurate orbital energy modeling of conjugated molecules

Bhatta

Pellicane

Tsige

2015

Computational and Theoretical Chemistry

View full text Add to dashboard Cite

a b s t r a c tDensity functional theory (DFT) calculations with range-separated (RS) functionals are important for orbital energy modeling of conjugated molecules that involve charge transfer excitation. However, the accuracy of the computed results depends on the range-separation parameter (w), and the optimal values of w for a wide range of conjugated systems has hitherto been missing. Herein, orbital energy modeling of twelve representative conjugated molecules, that are promising electron-donors in bulk heterojunction-based organic photovoltaic devices, are benchmarked using DFT and time-dependent DFT (TD-DFT) with three RS functionals (LC-BLYP, wB97XD and CAM-B3LYP). The results using the RS functionals under consideration with default values of w deviate largely from the experimental values (mean signed error (MSE) on HOMO are 2.1 eV, 0.93 eV and 1.5 eV, and MSE on vertical excitation energies are 0.47 eV, 0.55 eV and 0.82 eV, respectively). Computation of orbital energies using tuned range-separation parameter for these RS functionals in the range of 0.05 6 w P 0.5 Bohr À1 indicates that w plays a significant role on the accuracy of the ground and the excited state energies. We found that the accurate orbital energies of conjugated systems can be predicted using values of w between 0.1 and 0.15 Bohr À1 , much smaller than the default values of 0.47, 0.33 and 0.20 Bohr À1 used in LC-BLYP, CAM-B3LYP and wB97XD, respectively.

show abstract

Assessing long-range corrected functionals with physically-adjusted range-separated parameters for calculating the polarizability and the second hyperpolarizability of polydiacetylene and polybutatriene chains

Cited by 87 publications

References 60 publications

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

On the applicability of time‐dependent density functional theory (TDDFT) and semiempirical methods to the computation of excited‐state potential energy surfaces of perylene‐based dye‐aggregates

Polarizabilities of π-Conjugated Chains Revisited: Improved Results from Broken-Symmetry Range-Separated DFT and New CCSD(T) Benchmarks

Tuning range-separated DFT functionals for accurate orbital energy modeling of conjugated molecules

Contact Info

Product

Resources

About