Absorption of DCM Dye in Ethanol: Experimental and Time Dependent Density Functional Study
Authors
Abstract:
Experimental and theoretical absorption spectra of [2-[2-[4-(dimethylamino) phenyl]ethenyl]-6-methyl-4H- pyran-4-ylidene]-propanedinitrile (DCM) have been studied. UV-Visible (UV-Vis.) absorption spectrum of DCM has been reported after its synthesis. Two relatively intense peaks appeared at 473 and 362 nm respectively. A theoretical investigation on the electronic structure of DCM is presented in an effort to rationalize our experimental results. Theoretical results have been obtained with a polarizable continuum model time-dependent density functional theory (PCM-TD-DFT) approach. At first, a vast functional benchmark has been performed to determine a suitable approach for determination of electronic structure and UV-Vis. absorption spectrum of DCM. In a second step, we evaluated the impact of the atomic basis set on the electronic transition energies using a large panel of Pople’s basis sets ,up to the 6-31+G(3df,2p) and also a correlation consistent basis set, cc-pVTZ. It turns out that the selected basis set has a relatively finite influence on the calculated electronic transition energies as well as the topology of the absorption shape, but both are significantly affected by the chosen functional. In the present case, no single functional simultaneously provides highly accurate positions and intensities of the different bands, but mPW1PBE and mPW1LYP appear to be a good compromise. The mPW1PBE along with medium basis sets produced both absorption bands with maximum peaks about 463 and 346 nm. At all stages, ethanol has been chosen as a solvent environment. To improve the accuracy of first electronic excitation, a complete analysis of the origin of the band shape using TD-DFT vibrational couplings was performed. Finally the computed transition energy was corrected to 472 nm which was in excellent agreement with experiments.
similar resources
Time-dependent density functional theory (TDDFT) modelling of Pechmann dyes: from accurate absorption maximum prediction to virtual dye screening.
The red Pechmann dye (λ(max) = 550 nm) is the exo-dimer of 4-phenyl-3-butenolide connected at the α-carbon by a double bond in a trans-fashion. The ring system is easily rearranged to the trans-endo-fused bicyclic 6-membered lactone dimer (yellow). Both lactones can be singly or doubly amidated with primary amines leading to further colour changes. The nature of the core heterocycle (exo- vs. e...
full textTime-dependent density functional theory.
Time-dependent density functional theory (TDDFT) can be viewed as an exact reformulation of time-dependent quantum mechanics, where the fundamental variable is no longer the many-body wave function but the density. This time-dependent density is determined by solving an auxiliary set of noninteracting Schrodinger equations, the Kohn-Sham equations. The nontrivial part of the many-body interacti...
full textTime-Dependent Density Functional Theory
c 2006 by John von Neumann Institute for Computing Permission to make digital or hard copies of portions of this work for personal or classroom use is granted provided that the copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise requires prior specific permission by the publisher mentio...
full textProgress in time-dependent density-functional theory.
The classic density-functional theory (DFT) formalism introduced by Hohenberg, Kohn, and Sham in the mid-1960s is based on the idea that the complicated N-electron wave function can be replaced with the mathematically simpler 1-electron charge density in electronic structure calculations of the ground stationary state. As such, ordinary DFT cannot treat time-dependent (TD) problems nor describe...
full textExcitations in time-dependent density-functional theory.
An approximate solution to the time-dependent density-functional theory response equations for finite systems is developed, yielding corrections to the single-pole approximation. These explain why allowed Kohn-Sham transition frequencies and oscillator strengths are usually good approximations to the true values, and why sometimes they are not. The approximation yields simple expressions for Gö...
full textMy Resources
Journal title
volume 12 issue None
pages 43- 56
publication date 2018-01
By following a journal you will be notified via email when a new issue of this journal is published.
Hosted on Doprax cloud platform doprax.com
copyright © 2015-2023