1,721,209 research outputs found
Control of Coherences and Optical Responses of Pigment-Protein Complexes by Plasmonic Nanoantennae
No full textThe key for light-harvesting in pigment-protein complexes are molecular excitons, delocalized excited states comprising a superposition of excitations at different molecular sites. There is experimental evidence that the optical response due to such excitons can be largely affected by plasmonic nanoantennae. Here we employ a multiscale approach combining time-dependent density functional theory and polarizable classical models to study the optical behavior of the LH2 complex present in bacteria when interacting with a gold nanorod. The simulation not only reproduces the experiments but also explains their molecular origin. By tuning the chromophoric unit and selectively switching on/off the excitonic interactions, as well as by exploring different setups, we clearly show that the dramatic enhancement in the optical response, unexpectedly, is not accompanied by changes in the coherences. Instead polarization effects are dominant. These results can be used to design an optimal control of the light-harvesting process through plasmonic nanoantennae
Exciton properties and optical spectra of light harvesting complex II from a fully atomistic description
Full text linkWe present a fully atomistic simulation of linear optical spectra (absorption, fluorescence and circular dichroism) of the Light Harvesting Complex II (LHCII) trimer using a hybrid approach, which couples a quantum chemical description of the chlorophylls with a classical model for the protein and the external environment (membrane and water). The classical model uses a polarizable Molecular Mechanics force field, thus allowing mutual polarization effects in the calculations of the excitonic properties. The investigation is performed both on the crystal structure and on structures generated by a μs long classical molecular dynamics simulation of the complex within a solvated membrane. The results show that this integrated approach not only provides a good description of the excitonic properties and optical spectra without the need for additional refinements of the excitonic parameters, but it also allows an atomistic investigation of the relative importance of electronic, structural and environment effects in determining the optical spectra
Fast evaluation of the geometries and properties of excited molecules in solution: a Tamm-Dancoff model with application to the 4-dimethyaminobenzonitrile
No full textSOLUTE-SOLVENT ELECTROSTATIC INTERACTIONS WITH NONHOMOGENEOUS RADIAL DIELECTRIC FUNCTIONS
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Medium effects on the molecular nonlinear optical properties: Theory and applications in the polarizable continuum model
No full textQuantum-Mechanical Continuum Solvation Study of the Polarizability of Halides at the Water/Air Interface
No full textMultireference Perturbation CI methods for solvated systems described within the polarizable continuum model
No full textWe present a method to include solvent effects described within the polarizable continuum model into the CIPSI multireference perturbation algorithm. In the methodology we have formulated and implemented, solvent interactions are explicitly included in the configuration interaction scheme and in the following perturbative corrections, through proper operators. The nonlinear character induced by such operators leads to an iterative procedure in which solute and solvent can mutually equilibrate. Applications to the electronic excitation spectrum of formamide are considered. In these cases, effects due to an incomplete electrostatic response of the solvent nonequilibrium model as well as repulsion interactions between solute and solvent have been included in the quantum mechanical description
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