Long-Range Particle Emission in Coincidence with Fission at Moderate Excitation Energies

1964 ◽  
Vol 133 (3B) ◽  
pp. B724-B731 ◽  
Author(s):  
J. A. Coleman ◽  
A. W. Fairhall ◽  
I. Halpern
Keyword(s):  
Long Range ◽  
Particle Emission ◽  
Excitation Energies

scholarly journals Long-Range Corrected DFT Calculations of First Hyperpolarizabilities and Excitation Energies of Metal Alkynyl Complexes

ChemPhysChem ◽  
2018 ◽  
Vol 19 (12) ◽  
pp. 1537-1546 ◽  
Author(s):  
Mahesh S. Kodikara ◽  
Rob Stranger ◽  
Mark G. Humphrey
Keyword(s):  
Dft Calculations ◽  
Long Range ◽  
Excitation Energies

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 Representation of the QM Subsystem for Long-Range Electrostatic Interaction in Non-Periodic Ab Initio QM/MM Calculations

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2500 ◽  
Author(s):  
Xiaoliang Pan ◽  
Edina Rosta ◽  
Yihan Shao
Keyword(s):  
Electron Density ◽  
Long Range ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Switching Function ◽  
Excitation Energies ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Distance Cutoff ◽  
Switching Functions

In QM/MM calculations, it is essential to handle electrostatic interactions between the QM and MM subsystems accurately and efficiently. To achieve maximal efficiency, it is convenient to adopt a hybrid scheme, where the QM electron density is used explicitly in the evaluation of short-range QM/MM electrostatic interactions, while a multipolar representation for the QM electron density is employed to account for the long-range QM/MM electrostatic interactions. In order to avoid energy discontinuity at the cutoffs, which separate the short- and long-range QM/MM electrostatic interactions, a switching function should be utilized to ensure a smooth potential energy surface. In this study, we benchmarked the accuracy of such hybrid embedding schemes for QM/MM electrostatic interactions using different multipolar representations, switching functions and cutoff distances. For test systems (neutral and anionic oxyluciferin in MM (aqueous and enzyme) environments), the best accuracy was acquired with a combination of QM electrostatic potential (ESP) charges and dipoles and two switching functions (long-range electrostatic corrections (LREC) and Switch) in the treatment of long-range QM/MM electrostatics. It allowed us to apply a 10Å distance cutoff and still obtain QM/MM electrostatics/polarization energies within 0.1 kcal/mol and time-dependent density functional theory (TDDFT)/MM vertical excitation energies within 10−3 eV from theoretical reference values.

Excitation energies expressed as orbital energies of Kohn–Sham density functional theory with long‐range corrected functionals

2020 ◽  
Vol 41 (14) ◽  
pp. 1368-1383 ◽  
Author(s):  
Kimihiko Hirao ◽  
Bun Chan ◽  
Jong‐Won Song ◽  
Kamala Bhattarai ◽  
Subrata Tewary
Keyword(s):  
Density Functional Theory ◽  
Long Range ◽  
Density Functional ◽  
Excitation Energies ◽  
Functional Theory ◽  
Orbital Energies

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>

LONG-RANGE-CORRECTED TIME-DEPENDENT DENSITY FUNCTIONAL STUDY ON ELECTRONIC SPECTRA OF FIVE-MEMBERED RING COMPOUNDS AND FREE-BASE PORPHYRIN

2006 ◽  
Vol 05 (04) ◽  
pp. 925-944 ◽  
Author(s):  
SEIKEN TOKURA ◽  
TAKAO TSUNEDA ◽  
KIMIHIKO HIRAO
Keyword(s):  
Long Range ◽  
Density Functional ◽  
Membered Ring ◽  
Oscillator Strengths ◽  
Time Dependent ◽  
Functional Study ◽  
Free Base ◽  
Excitation Energies ◽  
Ring Compounds ◽  
Dependent Density

Long-range-corrected time-dependent density functional theory (LC-TDDFT) was applied to five-membered ring compounds (cyclopentadiene, pyrrole, and furan molecules) and free-base porphyrin. The vertical π-π* and Rydberg excitation energies and corresponding oscillator strengths were calculated by LC-TDDFT. The LC scheme obviously improved the Rydberg excitation energies and oscillator strengths of these systems, which have been fairly underestimated by TDDFT with conventional pure and hybrid B3LYP functionals. On the whole, LC-TDDFT results were very close to the results of the ab initio symmetry-adapted cluster configuration interaction (SAC-CI) method for most excitations. However, LC-TDDFT is poor in describing doubly excited states such as the 1 1A1 state of five-membered ring compounds.

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