TIME-DEPENDENT DENSITY FUNCTIONAL THEORY STUDY ON DYNAMICS OF HYDROGEN BONDING IN EXCITED STATES OF TRANS-ACETANILIDE IN METHANOL SOLVENT

2012 ◽  
Vol 11 (02) ◽  
pp. 421-435 ◽  
Author(s):  
XIAOYU ZHANG ◽  
WEIPING ZHANG ◽  
FANKAI MENG
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Excited States ◽  
Electronic Spectra ◽  
Density Functional ◽  
Excitation Energies ◽  
Intermolecular Hydrogen Bonds ◽  
Functional Theory ◽  
Tddft Method

The hydrogen-bonding dynamics in both singlet and triplet excited states of the trans-acetanilide ( AA ) in methanol ( MeOH ) solvent was investigated using the time-dependent density functional theory (TDDFT) method. Geometric optimizations of the hydrogen-bonded AA–MeOH complexes considered here as well as the isolated AA and MeOH molecules were performed using density functional theory (DFT) method. At the same time, the TDDFT method was performed to calculate the electronic transition energies and corresponding oscillation strengths of all the compounds in the low-lying electronically excited states. In this study, only the intermolecular hydrogen bonds C=O⋯H–O and N–H⋯O–H can be formed. A theoretical forecast that changes of hydrogen bonds in the low-lying electronic excited states was proposed. We discussed not only ground-state geometric structures and electronic excitation energies but also frontier molecular orbitals and electron density transition. The intermolecular hydrogen bonds between AA and MeOH molecules play an important role in the geometric structures and electronic excitation energies. Zhao et al. have put forward the relationship between the electronic spectra and hydrogen bonding dynamics for the first time. According to Zhao's rule, a redshift of the relevant electronic spectra will appear if hydrogen bond is strengthened, while the hydrogen bond weakening can make an electronic spectra shift to blue.

A theoretical study of hydration effects on structural stability and hydrogen-bonding dynamics of 2′-deoxyguanosine 5′-monophosphate with different negative charges

2013 ◽  
Vol 91 (2) ◽  
pp. 169-175
Author(s):  
Weiping Zhang ◽  
Xiaoyu Zhang
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Negative Charge ◽  
Solvation Shell ◽  
Excitation Energies ◽  
Functional Theory ◽  
Hydrogen Bonding Dynamics

The effects of hydration on the ground-state structural stability and excited-state hydrogen-bonding dynamics of 2′-deoxyguanosine 5′-monophosphate (dGMP) carrying different negative charges were investigated with B3LYP/6–31+G(d,p) using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, respectively. Particularly, we not only considered the solvent effects by the polarizible continuum model (PCM), but also the first solvation shell was included explicitly. We demonstrated that the intramolecular hydrogen bond O2–H1···O3 will be weakened with the strengthening of the hydration. From the view of bond length, we can make a valid presumption that the site of negative charge will be the more preferable site of the hydration, and the preferable site may be changed because of the presence of other hydrogen bonds. Furthermore, we found that the first solvation shell had very little effect on the geometric structures except for the hydrogen bond P–O5···H5. By comparing the excitation energies, one important finding is that the changes in different electronic states are not obvious with the increase in n value when considering the PCM. Another finding is that the average interactions of hydrogen bonds may be strengthened with an increase of negative charge because of a decrease in excitation energies.

Multiconfiguration pair-density functional theory for doublet excitation energies and excited state geometries: the excited states of CN

2017 ◽  
Vol 19 (44) ◽  
pp. 30089-30096 ◽  
Author(s):  
Jie J. Bao ◽  
Laura Gagliardi ◽  
Donald G. Truhlar
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Excited States ◽  
Density Functional ◽  
Excitation Energies ◽  
Functional Theory ◽  
Pair Density

MC-PDFT is more accurate than CR-EOM-CCSD(T) or TDDFT when averaged over the first four adiabatic excitation energies of CN.

INVESTIGATION OF DOMINANT ELECTRON CONFIGURATIONS IN TIME-DEPENDENT DENSITY FUNCTIONAL THEORY

2005 ◽  
Vol 04 (01) ◽  
pp. 265-280 ◽  
Author(s):  
SUSUMU YANAGISAWA ◽  
TAKAO TSUNEDA ◽  
KIMIHIKO HIRAO
Keyword(s):  
Density Functional Theory ◽  
Small Molecules ◽  
Excited States ◽  
Density Functional ◽  
Time Dependent ◽  
Response Matrix ◽  
Excitation Energies ◽  
Functional Theory ◽  
Electron Transitions ◽  
Dependent Density

We investigated the electron configurations that are dominant in excited states of molecules in time-dependent density functional theory (TDDFT). By taking advantage of the discussion on off-diagonal elements in the TDDFT response matrix (Appel et al., Phys Rev Lett, 90, 043005, 2003), we can pick up electron transitions that contribute to an excitation of interest by making use of the diagonal elements of the TDDFT matrix. We can obtain approximate excitation energies by calculating a TDDFT submatrix, which is contracted for a list of collected transitions. This contracted TDDFT was applied to the calculation of excitation energies of the CO molecule adsorbing Pt 10 cluster and some prototype small molecules. Calculated results showed that a TDDFT excitation energy is dominated by a few electron configurations, unless severe degeneracy is involved.

scholarly journals A theoretical study on the red- and blue-shift hydrogen bonds of cis-trans formic acid dimer in excited states

2013 ◽  
Vol 11 (2) ◽  
pp. 171-179 ◽  
Author(s):  
Dapeng Yang ◽  
Yonggang Yang ◽  
Yufang Liu
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Formic Acid ◽  
Excited States ◽  
Density Functional ◽  
Blue Shift ◽  
Red Shift ◽  
Functional Theory ◽  
Photophysical Study ◽  
Tddft Method

AbstractThe excited states of cis-trans formic acid dimer and its monomers have been investigated by time-dependent density functional theory (TDDFT) method. The formation of intermolecular hydrogen bonds O1-H1...O2=C2 and C2-H2...O4=C1 induces bond length lengthening of the groups related to the hydrogen bond, while that of the C2-H2 group is shortened. It is demonstrated that the red-shift hydrogen bond O1-H1...O2=C2 and blue-shift hydrogen bond C2-H2...O4=C1 are both weakened when excited to the S1 state. Moreover, it is found that the groups related to the formation of red-shift hydrogen bond O1-H1...O2=C2 are both strengthened in the S1 state, while the groups related to the blue-shift hydrogen bond C2-H2...O4=C1 are both weakened. This will provide information for the photochemistry and photophysical study of red- and blue-shift hydrogen bond.

scholarly journals Hydrogen-bonding study of photoexcited 4-nitro-1,8-naphthalimide in hydrogen-donating solvents

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 621-627
Author(s):  
Jianfang Cao ◽  
Hongmei Wu ◽  
Yue Zheng ◽  
Fangyuan Nie ◽  
Ming Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Excited States ◽  
Density Functional ◽  
Intermolecular Hydrogen Bond ◽  
Excitation Energies ◽  
Hydrogen Bond Acceptor ◽  
Functional Theory ◽  
Electronically Excited ◽  
Hydrogen Bonded

AbstractThe solute–solvent interactions of 4-nitro-1,8-naphthalimide (4NNI) as a hydrogen bond acceptor in hydrogen donating methanol (MeOH) solvent in electronic excited states were investigated by means of the time-dependent density functional theory(TDDFT). We calculated the S0 state geometry optimizations, electronic transition energies and corresponding oscillation strengths of the low-lying electronically excited states for the isolated 4NNi and hydrogen-bonded 4NNi-(MeOH)1,4 complexes using the density functional theory (DFT) and TDDFT methods. The electronic excitation energies of the hydrogen-bonded complexes are correspondingly decreased compared to that of the isolated 4NNi, which revealed that the intermolecular hydrogen bond C=O···H–O and N=O···H–O in the hydrogen-bonded 4NNi-(MeOH)1,4 are strengthened in the electronically excited state. The calculated results are consistent with the mechanism that hydrogen bond strengthening will induce a redshift of the corresponding electronic spectra, while hydrogen bond weakening will cause a blueshift. Furthermore, we believe that the deduction we used to depict the trend of the hydrogen bond changes in excited states exists in many other fuorescent dyes in solution.

scholarly journals Excited states properties of organic molecules: from density functional theory to the GW and Bethe–Salpeter Green's function formalisms

2014 ◽  
Vol 372 (2011) ◽  
pp. 20130271 ◽  
Author(s):  
C. Faber ◽  
P. Boulanger ◽  
C. Attaccalite ◽  
I. Duchemin ◽  
X. Blase
Keyword(s):  
Density Functional Theory ◽  
Green’S Function ◽  
Excited States ◽  
Green's Function ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Many Body ◽  
Excitation Energies ◽  
Functional Theory ◽  
Organic Systems

Many-body Green's function perturbation theories, such as the GW and Bethe–Salpeter formalisms, are starting to be routinely applied to study charged and neutral electronic excitations in molecular organic systems relevant to applications in photovoltaics, photochemistry or biology. In parallel, density functional theory and its time-dependent extensions significantly progressed along the line of range-separated hybrid functionals within the generalized Kohn–Sham formalism designed to provide correct excitation energies. We give an overview and compare these approaches with examples drawn from the study of gas phase organic systems such as fullerenes, porphyrins, bacteriochlorophylls or nucleobases molecules. The perspectives and challenges that many-body perturbation theory is facing, such as the role of self-consistency, the calculation of forces and potential energy surfaces in the excited states, or the development of embedding techniques specific to the GW and Bethe–Salpeter equation formalisms, are outlined.

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