A hybrid TDDFT/MM investigation of the optical properties of aminocoumarins in water and acetonitrile solution

Sulpizi, Marialore; Carloni, Paolo; Hutter, Jürg; Röthlisberger, Ursula

doi:10.1039/b305846h

Cited by 58 publications

(74 citation statements)

References 48 publications

(83 reference statements)

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“…We also include the results from a QM/ MM-CPMD study (all water molecules are treated in MM fashion there). 8 statistics in the last section. Also, for the simpler model with 300 frozen water molecules, the larger statistics increases the average excitation energy by about 0.03-0.04 (compared to the single trajectory) to 2.99 eV.…”

Section: Spectra Simulationsmentioning

confidence: 99%

“…5,6 To overcome the high demands in computer time for larger systems, the CPMD approach can be combined with a classical molecular-mechanics treatment of the solvent. 7,8 Recently, we could show that the frozen-density embedding scheme 9 provides a valuable tool for the calculation of solvatochromic shifts. 10 In this scheme, the Kohn-Sham-like, oneelectron equations for embedded orbitals, eqs 20 and 21 in ref 9, integrated within the general framework of linear response TDDFT 11,12 are used to evaluate the electronic excitation energies localized on a predefined subsystem.…”

Section: Introductionmentioning

confidence: 99%

“…[21][22][23][24] Especially in ref 21, the importance of specific and inhomogeneous interactions between solvent and solute, which are necessarily neglected in continuum models, has been underlined. In ref 8, the excitation energies have been calculated for C151 in water and acetonitrile using QM/MM-CPMD. Solvent shifts have then been computed with respect to the vertical excitation energy of the molecule in vacuo (as a model for a nonpolar solvent), and they were found to reproduce the experimental shifts between nonpolar and polar solvents quite well.…”

Section: Introductionmentioning

confidence: 99%

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An Explicit Quantum Chemical Method for Modeling Large Solvation Shells Applied to Aminocoumarin C151

et al. 2005

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The absorption spectra of aminocoumarin C151 in water and n-hexane solution are investigated by an explicit quantum chemical solvent model. We improved the efficiency of the frozen-density embedding scheme, as used in a former study on solvatochromism (J. Chem. Phys. 2005, 122, 094115) to describe very large solvent shells. The computer time used in this new implementation scales approximately linearly (with a low prefactor) with the number of solvent molecules. We test the ability of the frozen-density embedding to describe specific solvent effects due to hydrogen bonding for a small example system, as well as the convergence of the excitation energy with the number of solvent molecules considered in the solvation shell. Calculations with up to 500 water molecules (1500 atoms) in the solvent system are carried out. The absorption spectra are studied for C151 in aqueous or n-hexane solution for direct comparison with experimental data. To obtain snapshots of the dye molecule in solution, for which subsequent excitation energies are calculated, we use a classical molecular dynamics (MD) simulation with a force field adapted to first-principles calculations. In the calculation of solvatochromic shifts between solvents of different polarity, the vertical excitation energy obtained at the equilibrium structure of the isolated chromophore is sometimes taken as a guess for the excitation energy in a nonpolar solvent. Our results show that this is, in general, not an appropriate assumption. This is mainly due to the fact that the solute dynamics is neglected. The experimental shift between n-hexane and water as solvents is qualitatively reproduced, even by the simplest embedding approximation, and the results can be improved by a partial polarization of the frozen density. It is shown that the shift is mainly due to the electronic effect of the water molecules, and the structural effects are similar in n-hexane and water. By including water molecules, which might be directly involved in the excitation, in the embedded region, an agreement with experimental values within 0.05 eV is achieved.

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Section: Spectra Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Explicit Quantum Chemical Method for Modeling Large Solvation Shells Applied to Aminocoumarin C151

et al. 2005

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“…[1][2][3] These shifts are caused by a different stabilization of ground and excited states by the solvent within the Franck-Condon region, i.e., without a reorientation of the solvent molecules upon absorption or emission. In recent time, several attempts have been made to model the solvatochromic shifts of simple compounds such as acetone, 4,5 triazines or tetrazines, [6][7][8] solvatochromic organic dyes, [9][10][11] or transition metal compounds [12][13][14][15] with different explicit or implicit models for the solvent.…”

Section: Introductionmentioning

confidence: 99%

The merits of the frozen-density embedding scheme to model solvatochromic shifts

Neugebauer

Louwerse

Baerends

et al. 2005

The Journal of Chemical Physics

235

373

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We investigate the usefulness of a frozen-density embedding scheme within density-functional theory ͓J. Phys. Chem. 97, 8050 ͑1993͔͒ for the calculation of solvatochromic shifts. The frozen-density calculations, particularly of excitation energies have two clear advantages over the standard supermolecule calculations: ͑i͒ calculations for much larger systems are feasible, since the time-consuming time-dependent density functional theory ͑TDDFT͒ part is carried out in a limited molecular orbital space, while the effect of the surroundings is still included at a quantum mechanical level. This allows a large number of solvent molecules to be included and thus affords both specific and nonspecific solvent effects to be modeled. ͑ii͒ Only excitations of the system of interest, i.e., the selected embedded system, are calculated. This allows an easy analysis and interpretation of the results. In TDDFT calculations, it avoids unphysical results introduced by spurious mixings with the artificially too low charge-transfer excitations which are an artifact of the adiabatic local-density approximation or generalized gradient approximation exchange-correlation kernels currently used. The performance of the frozen-density embedding method is tested for the well-studied solvatochromic properties of the n → * excitation of acetone. Further enhancement of the efficiency is studied by constructing approximate solvent densities, e.g., from a superposition of densities of individual solvent molecules. This is demonstrated for systems with up to 802 atoms. To obtain a realistic modeling of the absorption spectra of solvated molecules, including the effect of the solvent motions, we combine the embedding scheme with classical molecular dynamics ͑MD͒ and Car-Parrinello MD simulations to obtain snapshots of the solute and its solvent environment, for which then excitation energies are calculated. The frozen-density embedding yields estimated solvent shifts in the range of 0.20-0.26 eV, in good agreement with experimental values of between 0.19 and 0.21 eV.

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“…Most often the QM approach is solved within Density Functional Theory (DFT) [8,9] to study ground state properties, and time-dependent DFT (TDDFT) [10,11] when excited states are involved as in the case of the optical properties [12,13,14]. TDDFT is computationally very efficient, yet its predictive power depends dramatically on the system and on the functional used to reproduce the exchange and correlation interactions.…”

Section: Pacs Numbersmentioning

confidence: 99%

Many‐body meets QM/MM: Application to indole in water solution

Conte

Ippoliti

Sole

et al. 2010

Physica Status Solidi (b)

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Aromatic chromophores are used as optical probes to investigate the structure of complex biological systems. For this purpose, it is crucial to understand the role of the bio‐chemical environment in the modification of their optical properties. Here we present a theoretical method to analyze this aspect on large scale systems, like biologically relevant molecules in aqueous solution. We combine many body perturbation theory with a quantum‐mechanics/molecular‐mechanics (QM/MM) approach. We include quasi‐particle and excitonic effects for the calculation of optical absorption spectra in a QM/MM scheme. In agreement with the experiments, we find that the solvent induces a redshift in the main spectral peak of indole, and we demonstrate this shift originates both from electrostatic and geometrical effects.magnified image

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A hybrid TDDFT/MM investigation of the optical properties of aminocoumarins in water and acetonitrile solution

Cited by 58 publications

References 48 publications

An Explicit Quantum Chemical Method for Modeling Large Solvation Shells Applied to Aminocoumarin C151

An Explicit Quantum Chemical Method for Modeling Large Solvation Shells Applied to Aminocoumarin C151

The merits of the frozen-density embedding scheme to model solvatochromic shifts

Many‐body meets QM/MM: Application to indole in water solution

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