Toward assessment of density functionals for vibronic coupling in two-photon absorption : A case study of 4-nitroaniline

• In this study, we predict vibronic two-photon absorption (TPA) spectra for 4-nitroaniline in vacuo. The simulations are performed using density functional theory and the approximate second-order coupled-cluster singles and doubles model CC2. Thereby we also demonstrate the possibility of simulations of vibronic TPA spectra with ab initio wavefunction methods that include electron correlation for medium-sized systems. A special focus is put on the geometric derivatives of the second-order transition moment and the dipole moment difference between the charge-transfer excited state and the ground state. The results of CC2 calculations bring new insight into the vibronic coupling mechanism in TPA spectra of 4-nitroniline and demonstrate that the mixed term is quite large and that it also exhibits a negative interference with the Franck-Condon contribution. CC2 method and several exchange-correlation functionals are used to predict vibronic two-photon absorption spectra of 4-nitroaniline.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

CC2 method

density functional theory

excited states

range-separated hybrid functionals

two-photon absorption

vibronic coupling

Calculations

Charge transfer

Ground state

Luminescence of organic solids

Numerical methods

Photons

Two photon processes

Charge-transfer excited state

Coupled-cluster singles and doubles

Exchange-correlation functionals

Hybrid functionals

Two photon absorption

Two-photon absorption spectrum

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