Excited state coupled cluster methods

Sneskov, Kristian; Christiansen, Ove

doi:10.1002/wcms.99

Cited by 221 publications

(249 citation statements)

References 101 publications

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“…One of the strongest attributes of applying LR and EOM approaches to excited states is their correct and balanced description of such state mixing. 44 It is important to note that the S 1 (ππ * )/S 2 (3s/πσ * ) interaction is only really important in a very narrow range of geometries where these states non-adiabatically couple. This means that for our results, only those shown at 1.2 Å have any degree of S 1 (ππ * )/S 2 (3s/πσ * ) mixing while all others can be thought of as essentially diabatic state properties.…”

Section: Theorymentioning

confidence: 99%

Ultraviolet relaxation dynamics of aniline, N, N-dimethylaniline and 3,5-dimethylaniline at 250 nm

Thompson

Saalbach

Crane

et al. 2015

The Journal of Chemical Physics

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Time-resolved photoelectron imaging was used to investigate the electronic relaxation dynamics of gas-phase aniline, N, N-dimethylaniline, and 3,5-dimethylaniline following ultraviolet excitation at 250 nm. Our analysis was supported by ab initio coupled-cluster calculations evaluating excited state energies and (in aniline) the evolution of a range of excited state physical properties as a function of N-H bond extension. Due to a lack of consistency between several earlier studies undertaken in aniline, the specific aim of this present work was to gain new insight into the previously proposed non-adiabatic coupling interaction between the two lowest lying singlet excited states S1(ππ(∗)) and S2(3s/πσ(∗)). The methyl-substituted systems N, N-dimethylaniline and 3,5-dimethylaniline were included in order to obtain more detailed dynamical information about the key internal molecular coordinates that drive the S1(ππ(∗))/S2(3s/πσ(∗)) coupling mechanism. Our findings suggest that in all three systems, both electronic states are directly populated during the initial excitation, with the S2(3s/πσ(∗)) state then potentially decaying via either direct dissociation along the N-X stretching coordinate (X = H or CH3) or internal conversion to the S1(ππ(∗)) state. In aniline and N, N-dimethylaniline, both pathways most likely compete in the depletion of S2(3s/πσ(∗)) state population. However, in 3,5-dimethylaniline, only the direct dissociation mechanism appears to be active. This is rationalized in terms of changes in the relative rates of the two decay pathways upon methylation of the aromatic ring system.

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Section: Theorymentioning

confidence: 99%

Ultraviolet relaxation dynamics of aniline, N, N-dimethylaniline and 3,5-dimethylaniline at 250 nm

Thompson

Saalbach

Crane

et al. 2015

The Journal of Chemical Physics

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“…The performance of these methods in the calculation of vertical electronic excitation energies or even 0-0 transitions is well documented for ADC (2) [10][11][12][13][14][15][16] and CC2 [10,11,[17][18][19][20][21][22][23][24] but not for SOPPA. Vertical electronic excitation energies * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Performance of SOPPA-based methods in the calculation of vertical excitation energies and oscillator strengths

et al. 2015

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We present two new modifications of the second-order polarization propagator approximation (SOPPA), SOPPA(SCS-MP2) and SOPPA(SOS-MP2), which employ either spin-component-scaled or scaled opposite-spin MP2 correlation coefficients instead of the regular MP2 coefficients. The performance of these two methods, the original SOPPA method as well as SOPPA(CCSD) and RPA(D) in the calculation of vertical electronic excitation energies and oscillator strengths is investigated for a large benchmark set of 28 medium-sized molecules with 139 singlet and 71 triplet excited states. The results are compared with the corresponding CC3 and CASPT2 results from the literature for both the TZVP set and the larger and more diffuse aug-cc-pVTZ basis set. In addition, the results with the aug-cc-pVTZ basis set are compared with the theoretical best estimates for this benchmark set. We find that the original SOPPA method gives overall the smallest mean deviations from the reference values and the most consistent results

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“…6 The principal application of CC2 is in the determination of response properties. 7 In particular, CC2 is usually applied in cases that are too large for a more complete CC theory and that would be problematic for lower-scaling methods such as time-dependent Hartree-Fock (TDHF) or density functional theory (TDDFT). One of the most common applications of CC2 is in the determination of excitation energies.…”

Section: Introductionmentioning

confidence: 99%

Quartic scaling second-order approximate coupled cluster singles and doubles via tensor hypercontraction: THC-CC2

Hohenstein

Kokkila

Parrish

et al. 2013

The Journal of Chemical Physics

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The second-order approximate coupled cluster singles and doubles method (CC2) is a valuable tool in electronic structure theory. Although the density fitting approximation has been successful in extending CC2 to larger molecules, it cannot address the steep O(N(5)) scaling with the number of basis functions, N. Here, we introduce the tensor hypercontraction (THC) approximation to CC2 (THC-CC2), which reduces the scaling to O(N(4)) and the storage requirements to O(N(2)). We present an algorithm to efficiently evaluate the THC-CC2 correlation energy and demonstrate its quartic scaling. This implementation of THC-CC2 uses a grid-based least-squares THC (LS-THC) approximation to the density-fitted electron repulsion integrals. The accuracy of the CC2 correlation energy under these approximations is shown to be suitable for most practical applications.

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Excited state coupled cluster methods

Cited by 221 publications

References 101 publications

Ultraviolet relaxation dynamics of aniline, N, N-dimethylaniline and 3,5-dimethylaniline at 250 nm

Ultraviolet relaxation dynamics of aniline, N, N-dimethylaniline and 3,5-dimethylaniline at 250 nm

Performance of SOPPA-based methods in the calculation of vertical excitation energies and oscillator strengths

Quartic scaling second-order approximate coupled cluster singles and doubles via tensor hypercontraction: THC-CC2

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