Vibronic absorption spectra and excited states of acridine red dye in aqueous solution: TD-DFT/DFT study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Victor V. Kostjukov
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Hydrogen Bonds ◽  
Absorption Spectra ◽  
Excited States ◽  
Dipole Moments ◽  
Basis Set ◽  
Calculated Spectrum ◽  
Solvent Model ◽  
Acridine Red

Abstract The vibronic absorption spectra of acridine red (AR) xanthene dye in an aqueous solution using 40 hybrid functionals, the 6-31++G(d,p) basis set, and the IEFPCM solvent model were calculated. It turned out that the O3LYP functional provided the best agreement with the experiment in the positions of the main maximum and the short-wavelength subband (shoulder). The calculations showed that this shoulder is vibronic. At the same time, the shoulder intensity in the calculated spectrum turned out to be lower than in the experimental one. Apparently, insignificant dimerization, which occurs even at low concentrations of the dye in solution, contributes to the shoulder of the experimental absorption spectrum. Various parameters of the AR cation in the ground and excited states (IR spectra, atomic charges, dipole moments, and transition moment) were calculated. Maps of the distribution of electron density and electrostatic potential have been built. The influence of the strong hydrogen bonds of the dye with three water molecules on the absorption spectrum was analyzed. It has been shown that these bonds are strengthened upon AR excitation. The strengthening of two hydrogen bonds with water upon excitation leads to a lowering of the potential energy surface of the excited state, which causes a decrease in the excitation energy (i.e., an increase in the wavelength of the absorbed photon) as compared to a purely implicit specification of the water environment. Therefore, explicit assignment of waters strongly bound to the dye leads to spectrum redshift.

scholarly journals TD-DFT/DFT study of Toluidine blue O in aqueous solution: vibronic transitions and electronic properties

2021 ◽  
Author(s):  
Lyudmila Kostjukova ◽  
Svetlana Leontieva ◽  
Victor Kostjukov
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Toluidine Blue ◽  
Density Functional ◽  
Dipole Moments ◽  
Basis Set ◽  
Functional Theory ◽  
Solvent Models ◽  
Td Dft ◽  
Vibronic Transitions

The vibronic absorption spectrum of Toluidine blue O (TBO) dye in an aqueous solution was calculated using the time-dependent density functional theory (TD-DFT). The calculations were performed using all hybrid functionals supported by Gaussian16 software and 6-31++G(d,p) basis set with IEFPCM and SMD solvent models. The IEFPCM gave underestimated values of λmax in comparison with the experiment, what is a manifestation of the TD-DFT “cyanine failure”. However, the SMD made it possible to obtain good agreement between calculated and experimental spectra. The best fit was achieved using the X3LYP functional. The dipole moments and atomic charges of the ground and excited states of the TBO molecule were calculated. Photoexcitation leads to an increase in the dipole moment of the dye molecule. An insignificant photoinduced electron transfer was found in the central ring of the chromophore of the TBO molecule. Vibronic transitions play a significant role in the absorption spectrum of the dye.

Quantum chemical computations on rotational isomers of hydrogen nitrite and nitritomethane

1982 ◽  
Vol 381 (1781) ◽  
pp. 443-455 ◽  
Keyword(s):  
Excited States ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Basis Set ◽  
Electronic Transitions ◽  
Rotational Isomers ◽  
Transition Structures ◽  
Quantum Chemical Computations ◽  
Split Valence ◽  
Good Agreement

Ab initio molecular-orbital computations with a split-valence 4-31G basis set have been carried out on syn- and antiperiplanar conformers of both HONO and H 3 CONO, and on the transition structures in the unimolecular isomerization process. Calculated values of geometric structural and rotational parameters, dipole moments, wavenumbers of vibrational transitions, energies of vertical electronic transitions to both neutral and ionized excited states, and thermodynamic properties are compared with experimental data; generally good agreement is found. No explanation of the anomalous stability of antiperiplanar HONO has been discovered.

scholarly journals Nonadiabatic Absorption Spectra and Ultrafast Dynamics of DNA and RNA Photoexcited Nucleobases

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1743
Author(s):  
James A. Green ◽  
Martha Yaghoubi Jouybari ◽  
Daniel Aranda ◽  
Roberto Improta ◽  
Fabrizio Santoro
Keyword(s):  
Absorption Spectra ◽  
Excited States ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Basis Set ◽  
Ultrafast Dynamics ◽  
Effective Population ◽  
Dna And Rna ◽  
Vibronic Spectra ◽  
Effective Wave

We have recently proposed a protocol for Quantum Dynamics (QD) calculations, which is based on a parameterisation of Linear Vibronic Coupling (LVC) Hamiltonians with Time Dependent (TD) Density Functional Theory (TD-DFT), and exploits the latest developments in multiconfigurational TD-Hartree methods for an effective wave packet propagation. In this contribution we explore the potentialities of this approach to compute nonadiabatic vibronic spectra and ultrafast dynamics, by applying it to the five nucleobases present in DNA and RNA. For all of them we computed the absorption spectra and the dynamics of ultrafast internal conversion (100 fs timescale), fully coupling the first 2–3 bright states and all the close by dark states, for a total of 6–9 states, and including all the normal coordinates. We adopted two different functionals, CAM-B3LYP and PBE0, and tested the effect of the basis set. Computed spectra are in good agreement with the available experimental data, remarkably improving over pure electronic computations, but also with respect to vibronic spectra obtained neglecting inter-state couplings. Our QD simulations indicate an effective population transfer from the lowest energy bright excited states to the close-lying dark excited states for uracil, thymine and adenine. Dynamics from higher-energy states show an ultrafast depopulation toward the more stable ones. The proposed protocol is sufficiently general and automatic to promise to become useful for widespread applications.

Terahertz Pulsed Spectroscopy as a New Tool for Measuring the Structuring Effect of Solutes on Water

2005 ◽  
Vol 59 (4) ◽  
pp. 505-510 ◽  
Author(s):  
N. Kaun ◽  
J. R. Baena ◽  
D. Newnham ◽  
B. Lendl
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Spectral Region ◽  
Blue Shift ◽  
Water Molecules ◽  
Mid Infrared ◽  
Stretch Vibration ◽  
Terahertz Pulsed Spectroscopy ◽  
Ionic Solutes

Absorption spectra of aqueous solution of “chaotropes” (structure maker) and “kosmotropes” (structure breaker) have been recorded in the mid-infrared (MIR) and terahertz (THz) spectral region. A different impact of the two groups of solutes on the absorption spectrum of water was found in the recorded THz spectra. A concentration-dependent increased absorption across the investigated THz spectral region (0.04–2 THz, 1.3–66 cm−1, respectively) has been recorded for all studied chaotropic solutions, whereas the opposite has been obtained for kosmotrope containing solutions. In the case of ionic solutes a further increase in absorption towards higher frequencies was measured. The distinction between chaotrope and kosmotrope solutes was, as expected, also possible in the MIR spectral region. Depending on the structure-forming effect of the solute the OH stretch vibration of the water (around 3400 cm−1) was slightly shifted. A red shift has been observed for solution of kosmotropes, whereas a blue shift was observed in the case of solutions containing chaotropes. Compared to the MIR spectral region the structure influencing effect of solutes can be more efficiently studied in the THz spectral region, which provides information from interactions between neighboring water molecules.

Potential energy curves and dipole moment of NF molecule with inner electron correlation

2015 ◽  
Vol 93 (12) ◽  
pp. 1544-1550 ◽  
Author(s):  
Mingjie Wan ◽  
Huafeng Luo ◽  
Chengguo Jin ◽  
Duohui Huang ◽  
Fanhou Wang
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Correlation Energy ◽  
Dipole Moments ◽  
Electronic States ◽  
Spectroscopic Properties ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Triplet States ◽  
Singlet And Triplet States

The potential energy curves and dipole moments for the low-lying electronic states of the NF molecule are found by using highly accurate multireference configuration interaction plus the Davidson correction with the AV5Z basis set. All 16 electrons are used in the correlation energy calculations, which are used to characterize the spectroscopic properties of a manifold for singlet and triplet states. X3Σ–, a1Δ, b1Σ+, A3Π, 23Σ–, 23Π, 21Δ, 33Σ–, 13Σ+, and 13Δ electronic states correlate with the two lowest dissociation channels N(4Su) + F(2Pu) and N(2Du) + F(2Pu) are investigated. Note that the b1Σ+ state has two depth wells, but only one depth well was observed in the experiment. The spectroscopic parameters (Re, ωe, ωeχe, De, Be, and Te) are derived, which are in excellent agreement with the available experimental data and the other theoretical values. The molecular parameters and dipole moments for the ground and excited states are also obtained.

scholarly journals Computing molecular excited states on a D-Wave quantum annealer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander Teplukhin ◽  
Brian K. Kendrick ◽  
Susan M. Mniszewski ◽  
Yu Zhang ◽  
Ashutosh Kumar ◽  
...  
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Dipole Moments ◽  
Molecular Geometry ◽  
Oscillator Strengths ◽  
Time Dependent ◽  
Basis Set ◽  
Quantum Computers ◽  
Transition Dipole ◽  
D Wave

AbstractThe possibility of using quantum computers for electronic structure calculations has opened up a promising avenue for computational chemistry. Towards this direction, numerous algorithmic advances have been made in the last five years. The potential of quantum annealers, which are the prototypes of adiabatic quantum computers, is yet to be fully explored. In this work, we demonstrate the use of a D-Wave quantum annealer for the calculation of excited electronic states of molecular systems. These simulations play an important role in a number of areas, such as photovoltaics, semiconductor technology and nanoscience. The excited states are treated using two methods, time-dependent Hartree–Fock (TDHF) and time-dependent density-functional theory (TDDFT), both within a commonly used Tamm–Dancoff approximation (TDA). The resulting TDA eigenvalue equations are solved on a D-Wave quantum annealer using the Quantum Annealer Eigensolver (QAE), developed previously. The method is shown to reproduce a typical basis set convergence on the example $$\hbox {H}_2$$ H 2 molecule and is also applied to several other molecular species. Characteristic properties such as transition dipole moments and oscillator strengths are computed as well. Three potential energy profiles for excited states are computed for $$\hbox {NH}_3$$ NH 3 as a function of the molecular geometry. Similar to previous studies, the accuracy of the method is dependent on the accuracy of the intermediate meta-heuristic software called qbsolv.

scholarly journals Исследование диэлектрических свойств полости кукурбитурила на основе эффекта сольватохромизма стирилового красителя при образовании комплекса включения

2019 ◽  
Vol 126 (4) ◽  
pp. 391
Author(s):  
А.С. Степко ◽  
Н.А. Лобова ◽  
П.В. Лебедев-Степанов
Keyword(s):  
Absorption Spectrum ◽  
Dielectric Properties ◽  
Dipole Moments ◽  
Molecular Structures ◽  
Basis Set ◽  
Theoretical Evaluation ◽  
Guest Molecules ◽  
Td Dft ◽  
Effective Dielectric Permittivity ◽  
Dielectric And Optical Properties

AbstractA new approach to the theoretical evaluation of the local dielectric properties of media that contain an organic dye acting as a nanoprobe is proposed. The method is checked so as to evaluate the dielectric properties of the host molecule in a supramolecular inclusion complex from the experimentally measured shift of the optical absorption spectrum of the guest molecules (dye) after the complex formation. Using the Onsager–Liptay model, the dielectric properties of the cucurbit[7]uril cavity was theoretically estimated by analyzing the experimentally measured shift of the absorption spectrum of 1-(3-ammoniopropyl)-4-[(E)-2-(3,4-dimethoxyphenyl)-ethenyl]-pyridinium dication of the dye after it forms a complex with cucurbit[7]uril in an aqueous solution. To parameterize the Onsager–Liptay equation, the positions of the absorption spectral maxima of the dye under study were experimentally measured in the following solvents with known dielectric and optical properties: methanol, ethanol, 1-propanol, 1-butanol, and water. When calculating molecular structures, dipole moments of the ground and excited states, and polarizability, the TD-DFT quantum chemical method with the CAM-B3LYP functional in the 6-311G(d,p) basis set was used within the Gamess (United States) software package. The obtained theoretical value of the effective dielectric permittivity of the cavity (about 13) is in good agreement with the published value.

Electronic absorption, fluorescence and polarisation spectra of α,β-diamino-9,10-anthraquinones and their interpretation by the method of configuration analysis

1982 ◽  
Vol 47 (10) ◽  
pp. 2604-2614 ◽  
Author(s):  
Miloš Nepraš ◽  
Miloš Titz ◽  
Jürgen Fabian ◽  
Bohuslav Gaš
Keyword(s):  
Polyvinyl Alcohol ◽  
Absorption Spectra ◽  
Excited States ◽  
Wavelength Range ◽  
Electronic Absorption ◽  
Frequency Dependent ◽  
Absorption Frequency

On the basis of measurement of absorption frequency-dependent polarisation spectra of fluorescence (APF) and dichroism on oriented polyvinyl alcohol sheets, interpretation has been carried out of absorption spectra of α,β-diamino-9,10-anthraquinones in the wavelength range 250 to 600 nm. Character of the excited states has been investigated by the method of configuration analysis (PPP-CA).

Simulation of UV Absorption Spectra and Relaxation Dynamics of Uracil and Uracil-Water Clusters

2020 ◽  
Author(s):  
Branislav Milovanović ◽  
Jurica Novak ◽  
Mihajlo Etinski ◽  
Wolfgang Domcke ◽  
Nadja Doslic
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Absorption Spectra ◽  
Absorption Spectroscopy ◽  
Water Clusters ◽  
Uv Absorption ◽  
Relaxation Dynamics ◽  
Nonradiative Relaxation ◽  
Uv Absorption Spectra ◽  
Uv Absorption Spectroscopy

Despite many studies, the mechanisms of nonradiative relaxation of uracil in the gas phase and in aqueous solution are still not fully resolved. Here we combine theoretical UV absorption spectroscopy...

scholarly journals Cooperation/Competition between Halogen Bonds and Hydrogen Bonds in Complexes of 2,6-Diaminopyridines and X-CY3 (X = Cl, Br; Y = H, F)

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 766
Author(s):  
Barbara Bankiewicz ◽  
Marcin Palusiak
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Main Role ◽  
Halogen Bonds ◽  
Topological Parameters ◽  
Leading Role ◽  
The Impact

The DFT calculations have been performed on a series of two-element complexes formed by substituted 2,6-diaminopyridine (R−PDA) and pyridine (R−Pyr) with X−CY3 molecules (where X = Cl, Br and Y = H, F). The primary aim of this study was to examine the intermolecular hydrogen and halogen bonds in the condition of their mutual coexistence. Symmetry/antisymmetry of the interrelation between three individual interactions is addressed. It appears that halogen bonds play the main role in the stabilization of the structures of the selected systems. However, the occurrence of one or two hydrogen bonds was associated with the favourable geometry of the complexes. Moreover, the impact of different substituent groups attached in the para position to the aromatic ring of the 2,6-diaminopyridine and pyridine on the character of the intermolecular hydrogen and halogen bonds was examined. The results indicate that the presence of electron-donating substituents strengthens the bonds. In turn, the presence of electron-withdrawing substituents reduces the strength of halogen bonds. Additionally, when hydrogen and halogen bonds lose their leading role in the complex formation, the nonspecific electrostatic interactions between dipole moments take their place. Analysis was based on geometric, energetic, and topological parameters of the studied systems.

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