Solvent Effects on Electronically Excited States Using the Conductor-Like Screening Model and the Second-Order Correlated Method ADC(2)

Abstract

The conductor-like screening model (COSMO) is used to treat solvent effects on excited states within a correlated method based on the algebraic-diagrammatic construction through second-order ADC(2). The origin of solvent effects is revisited, and it is pointed out that two types of contributions have to be considered. One effect is due to the change of the solute's charge distribution after excitation, which triggers a reorganization of the solvent. Initially, only the electronic degrees of freedom adapt to the new charge distribution (nonequilibrium case); for sufficiently long-lived states, the reorientation of the solvent molecules contributes, as well (equilibrium case). The second effect is the coupling of the transition densities to the fast (purely electronic) response of the solvent molecules, which can be viewed as excitonic coupling between solute and solvent molecules. This interaction is also responsible for the screening of excitonic couplings between spatially separated chromophores. While most previous implementations of comparable continuum solvation models only include either of both effects, we argue that both contributions should be taken into account. Both effects can significantly influence the excitation energy and excited state properties of the solute, as exemplified for the π-π* and n-π* excitations of acrolein, and no a priori reason exists to neglect either. The implementation is also tested for the excitonic coupling of the ethene dimer where linear response contributions are indispensable for recovering the screening effects due to the solvent. Example applications to larger cases are provided, too. We discuss the excitonic coupling in a linked dyad consisting of two perylene-tetracarboxy-diimide chromophores, and the solvent effects on an intramolecular charge-transfer state of 4-(N,N-dimethylamino)benzonitrile.

Explaining Level Inversion of the La and Lb States of Indole and Indole Derivatives in Polar Solvents

“…[25] To account for the effect of the solvent on the excitation energies an ADC(2) approach combined with a conductor-like solvation model (COSMO) is used. [26,27] We demonstrate that non-specific interactions with a dielectric medium can account for a large solvent shift in indole and related derivatives. Solvent polarity, represented by the dielectric constant of the solvent and its refractive index, stabilizes the energy of the L a state such that the L a state eventually becomes the lowest emitting state of indole.…”

Ab Initio Multiple Spawning Photochemical Dynamics of DMABN Using GPUs

“…Both ADC(2) and LR-TDDFT/ωPBE indicate that S 1 -(T)ICT is lower in energy than S 1 -LE in the gas phase (see also Ref. 18 ), but LR-TDDFT predicts a larger stability difference. In fact, high-level wavefunction methods suggest that the correct ordering is reversed, i.e.…”

“…Theory has not been able to unambiguously determine the fluorescence mechanism, although many electronic structure methods have been employed to probe the critical points of the S 1 potential energy surface in Curchod, et al -DMABN -Page 3 both gas and condensed phases. Electronic structure methods used to examine the details of the emission process have included linear-response time-dependent density functional theory [12][13][14] (LR-TDDFT), single-reference wavefunction methods such as TDHF/CIS, 15 DFT/SCI, 16 CC2, 17 and ADC(2), 18 and multi-reference wavefunction methods such as CASSCF [19][20][21] and CASPT2. [22][23][24][25] Even though a large number of experimental and theoretical data have been generated on the emission properties of DMABN and its chemical derivatives, much less information is available on the early nonadiabatic, i.e., non-Born-Oppenheimer, relaxation pathway following DMABN photoexcitation.…”

Solvent effects on optical excitations of poly para phenylene ethynylene studied by QM/MM simulations based on many-body Green's functions theory

“…Excitation energies in complex molecular environments, such as molecular aggregates or solute-solvent mixtures, can accurately be obtained by treating the subpart of interest quantum-mechanically and embedding it into an environment at molecular mechanics resolution [59][60][61][62]. This can be realized by representing the molecules in the MM region by a set of atomic properties such as static multipole moments Q a t (in spherical tensor representation [63], where t indicates the multipole rank and a the associated atom) and polarizabilities.…”