Singlet and triplet excitation energies

The CCS, CC2, CCSD, CC3 hierarchy has been designed specially for the calculation of frequency-dependent properties. In this hierarchy, a systematic improvement in the description of the dynamic electron correlation is obtained at each level. For example, comparing CCS, CC2, CCSD, CC3 with FCI singlet and triplet excitation energies showed that the errors decreased by about a factor 3 at each level in the coupled cluster hierarchy [18]. The CC3 error was as small as 0.016 eV and the accuracy of the CC3 excitation energies was comparable to the one of the CCSDT model [18]. 

Lowest singlet and triplet excitation energies of buckminsterfullerene in ev... 

Knowledge of the gas phase electron affinities for a series of molecules, such as the fluoroethylenes, provides new insight into substituent effects. The correlation between the trends in the singlet and triplet excitation energies of the neutral molecules and the quantity (IP - EA) is also examined. 

Fig. 6 Exciton trapping on organic matrix molecules with subsequent energy transfer. Exploitation of matrix singlet and triplet excitation energy requires the effectiveness of two independent processes of energy transfer. Such a matching of molecular energies might be difficult to achieve, when OLED emitter layers are developed, vibr. vibrational...

A wide variety of molecular properties can be accurately obtained with ADF. The time-dependent DFT implementation " yields UV/Vis spectra (singlet and triplet excitation energies, as well as oscillator strengths), frequency-dependent (hyper)polarizabilities (nonlinear optics), Raman intensities, and van der Waals dispersion coefficients. Rotatory strengths and optical rotatory dispersion (optical properties of chiral molecules ), as well as frequency-dependent dielectric functions for periodic structures, have been implemented as well. NMR chemical shifts and spin-spin couplingsESR (EPR) f-tensors, magnetic and electric hyperfme tensors are available, as well as more standard properties like IR frequencies and intensities, and multipole moments. Relativistic effects (ZORA and spin-orbit coupling) can be included for most properties. 

Factors that control electronic coupling, as manifested through electron transfer and singlet and triplet excitation energy transfer, are discussed for covalent donor-bridge-acceptor (DBA) systems. 

Della Sala, R, and Fabiano, E. (2011) Accurate singlet and triplet excitation energies using the Localized Hartree-Fock Kohn-Sham potential, Chent Phys., 391,19-26. 

Fabiano, E., Deiia Saia, F., Cingoiani, R., Weimer, M., and Gorling, A. [2005] Theoretical study of singlet and triplet excitation energies in oligothiophenes,/. Phys. Chem. A, 109,3078-3085. 

What combinations of creation and annihilation operators would produce, when acting on the closed-shell ground state, the singlet and triplet excited functions in Problem 3.8 Use second-quantization methods to obtain the singlet and triplet excitation energies (cf. Problem 3.9). [Hint Use ap , Upp, etc. to indicate explicitly the operators that create or annihilate an electron in [Pg.86]

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