scholarly journals Assessment of the Performance of Long-Range-Corrected Density Functionals for Calculating the Absorption Spectra of Silver Clusters

2013 ◽  
Vol 117 (20) ◽  
pp. 4267-4278 ◽  
Author(s):  
Franck Rabilloud
Keyword(s):  
Absorption Spectra ◽  
Long Range ◽  
Silver Clusters ◽  
Density Functionals

Reproduction of the UV-vis spectra of boron subphthalocyanine chloride in different solvents using time-dependent generalized Kohn–Sham density functionals with first solvation shell

2018 ◽  
Vol 22 (08) ◽  
pp. 670-678 ◽  
Author(s):  
Xue Chen ◽  
Wenlan Chen ◽  
Shaohui Zheng
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Solvation Shell ◽  
Photon Absorption ◽  
Ultraviolet Region ◽  
Density Functionals ◽  
Research Fields ◽  
Boron Subphthalocyanine ◽  
Experimental Absorption

Because of the unique physical, chemical and optical characteristics of boron subphthalocyanine chloride, it has been widely applied in different research fields and attracted global researchers. Deep insight into its UV-vis spectrum is required to understand the mechanism of the photon absorption of boron subphthalocyanine chloride in its condensed phase. In the present work, we utilize generalized Kohn–Sham density functionals with a non-equilibrium solvation model to simulate the UV-vis spectra of boron subphthalocyanine chloride in different solvents. Without considering the first solvation shell, we find that the slopes of lines drawn with [Formula: see text]B97XD and CAM-B3LYP results vs. experimental absorption wavelengths are close to 1.0 and root–mean–square deviations are less than 40 nm. We also find that the inclusion of the first solvation shell surrounding boron subphthalocyanine chloride monomers generally makes the calculated results worse. Finally, we discover that the simulated results overestimate oscillator strength of electronic absorption spectra in the ultraviolet region with respect to experimental spectra. These results imply that it may be important to consider the aggregation of solute molecules in order to understand the electronic absorption spectra of subPC in solution

Long-range corrected double-hybrid density functionals

2009 ◽  
Vol 131 (17) ◽  
pp. 174105 ◽  
Author(s):  
Jeng-Da Chai ◽  
Martin Head-Gordon
Keyword(s):  
Long Range ◽  
Density Functionals

scholarly journals Simplified Tuning of Long-Range Corrected Density Functionals for Use in Symmetry-Adapted Perturbation Theory

2021 ◽  
Author(s):  
Montgomery Gray ◽  
John Herbert
Keyword(s):  
Perturbation Theory ◽  
Asymptotic Behavior ◽  
Long Range ◽  
System Size ◽  
Second Order ◽  
Density Functionals ◽  
Hole Making ◽  
Large Systems ◽  
Automated Tuning ◽  
Order Dispersion

Long considered a failure, second-order symmetry-adapted perturbation theory (SAPT) based on Kohn-Sham orbitals, or SAPT(KS), can been resurrected for semiquantitative purposes using long-range corrected (LRC) density functionals whose asymptotic behavior is adjusted separately for each monomer. As in other contexts, correct asymptotic behavior can be enforced via "optimal tuning" of LRC functionals, based on the ionization energy theorem, but the tuning procedure is tedious, expensive for large systems, and comes with a troubling dependence on system size. Here, we show that essentially identical results are obtained using an automated tuning procedure based on the size of the exchange hole, making tuned "SAPT(wKS)" fast and convenient. In conjunction with SAPT-based methods that sidestep second-order dispersion, this procedure achieves benchmark-quality interaction energies, along with the usual SAPT energy decomposition, without the hassle of system-specific tuning.

scholarly journals 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

2021 ◽  
Author(s):  
Marcos Casanova Paez ◽  
Lars Goerigk
Keyword(s):  
Long Range ◽  
Chem Phys ◽  
Superior Performance ◽  
Spin Component ◽  
Density Functionals ◽  
Robust Methods ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Perturbative Part ◽  
Benchmark Sets

<div> <div> <div> <p>Following 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 functional 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 ωB88PP86 as the best unscaled method in this work. </p> </div> </div> </div>

scholarly journals ABSORPTION OF SOME SMALL SILVER CLUSTERS: DFT AND CASPT2 CALCULATIONS

2018 ◽  
Vol 55 (6A) ◽  
pp. 72
Author(s):  
Ngo Tuan Cuong
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Noble Gas ◽  
Silver Cluster ◽  
Dft Method ◽  
Basis Sets ◽  
Silver Clusters ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Td Dft

Two quantum chemical methods which are the time-dependent density functional theory (TD-DFT) and the complete active space CASPT2/CASSCF have been used in modeling absorption spectra of silver clusters Agn (n = 2, 3, 4, 6, 8). There is an overall good agreement between TD-DFT and CASPT2 results for transition energies. The absorption spectra of the Agn clusters examined can reasonably be simulated using the excitation energies obtained by either TD-DFT or CASPT2 method.  The main result emerged from this calculation is that the TD-DFT method is suitable for treatment of excited states of Ag clusters. The choice of specific functionals and basis sets to be used in some cases induces important effects on the calculated spectra. It is also noteworthy to mention that for some clusters, the neutral Ag6 for instance, the effect of noble gas environment is significant, while for some others such as the neutral Ag8, it is not. Therefore, carrying out TD-DFT calculations to reproduce and to assign a given structure to an experimental absorption spectrum of a silver cluster, it is not only to select suitable functionals but also to take enough effects of environments into account. 

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