Assessment of Conventional Density Functional Schemes for Computing the Dipole Moment and (Hyper)polarizabilities of Push−Pull π-Conjugated Systems†

2000 ◽  
Vol 104 (20) ◽  
pp. 4755-4763 ◽  
Author(s):  
Benoît Champagne ◽  
Eric A. Perpète ◽  
Denis Jacquemin ◽  
Stan J. A. van Gisbergen ◽  
Evert-Jan Baerends ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Density Functional ◽  
Conjugated Systems

Theoretical studies on the one- and two-photon absorption of tetrabenzoporphyrins and phthalocyanines

2004 ◽  
Vol 82 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Xin Zhou ◽  
Ai-Min Ren ◽  
Ji-Kang Feng ◽  
Xiao-Juan Liu
Keyword(s):  
Dipole Moment ◽  
Cross Sections ◽  
Density Functional ◽  
Transition Dipole Moment ◽  
Photon Absorption ◽  
Transition Dipole ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Order Of Magnitude ◽  
The One

The one-photon absorption (OPA) properties of tetrabenzoporphyrins (TBPs) and phthalocyanines (Pcs) were studied using the semiempirical ZINDO method and time-dependent density functional theory (TDDFT), respectively. The compared results confirmed that the semiempirical ZINDO method was reasonably reliable when calculating the OPA of tetrabenzoporphyrins and phthalocyanines. On the basis of the OPA properties obtained from the ZINDO method, two-photon absorption (TPA) properties of two series of molecules were investigated, using ZINDO and sum-over-states (SOS) methods. The results showed that the TPA cross-sections of all molecules were in the range of 220.6 × 10–50 – 345.9 × 10–50 cm4·s·photon–1, which were in the same order of magnitude as the values reported in the literature. The relatively larger δ(ω) value for Pcs with respect to that for corresponding TBPs originates from larger intramolecular charge transfer, which can be characterized by the difference of dipole moment between S0 and S1 and the transition dipole moment between S1 and S5.Key words: two-photon absorption, ZINDO, sum-over-states, tetrabenzoporphyrin, phthalocyanines.

scholarly journals Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

2020 ◽  
Author(s):  
Tianyu Zhu ◽  
Troy Van Voorhis
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid Water ◽  
Density Functional ◽  
Bulk Water ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Design Strategies ◽  
Total Electron Density ◽  
Total Electron

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

scholarly journals Quantum Chemistry of Cocaine and its Isomers I: Energetics, Reactivity and Solvation

2021 ◽  
Vol 75 ◽  
Author(s):  
Safa Ben Amara ◽  
Thorsten Koslowski ◽  
Ali Zaidi
Keyword(s):  
Dipole Moment ◽  
Solvent Effect ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Theoretical Perspective ◽  
Solvent Polarity ◽  
Stable Conformation ◽  
Functional Theory ◽  
Implicit Solvents ◽  
The Rich

ABSTRACT We investigate the rich stereochemistry of cocaine and its diastereoisomers from a theoretical perspective using density functional theory. The relative stability of the eight considered isomers is discussed, and a comparison of the corresponding internal coordinates is given. Our results reveal that the S-pseudococaine isomer is the most stable conformation, whereas the natural occurring isomer (R-cocaine) lies higher in energy. The different isomers' chemical reactivity is discussed based on the calculation of the hardness, softness, electrophilicity and dipole moment. It was found that the dipole moment varies over a broad range from 0.65 to 4.60 D, whereas the other properties are slightly modified. The solvent effect on the energy stability of the cocaine isomers was studied by considering chloroform, dimethyl-sulfoxide (DMSO) and water as implicit solvents. Our calculations show that the different isomers' energy order and their energy gaps are slightly modified due to solvent effects. However, in all cases, the S-pseudococaine remains the most stable isomer. However, the dipole moment and the chemical reactivity of the cocaine isomers increase with the solvent polarity. Keywords: Cocaine isomers,DFT, stability, solvent effect, chemical reactivity.

scholarly journals Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

2020 ◽  
Author(s):  
Tianyu Zhu ◽  
Troy Van Voorhis
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid Water ◽  
Density Functional ◽  
Bulk Water ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Design Strategies ◽  
Total Electron Density ◽  
Total Electron

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

scholarly journals Diffusion and Reptation Quantum Monte Carlo Study of the NaK Molecule

2018 ◽  
Author(s):  
Marc E. Segovia ◽  
Oscar Ventura
Keyword(s):  
Monte Carlo ◽  
Dipole Moment ◽  
Potential Energy ◽  
Dissociation Energy ◽  
Quantum Monte Carlo ◽  
Density Functional ◽  
Basis Set ◽  
Energy Curve ◽  
Dft Methods ◽  
Trial Wavefunction

<p>Diffusion Monte Carlo (DMC) and Reptation Monte Carlo (RMC) methods, have been applied to study some properties of the NaK molecule. Hartree-Fock (HF), Density Functional (DFT) and single and double configuration interaction (SDCI) wavefunctions with a valence quadruple zeta atomic natural orbital (VQZ/ANO) basis set were used as trial wavefunctions. Values for the potential energy curve, dissociation energy and dipole moment were calculated for all methods and compared with experimental results and previous theoretical derivations. Quantum Monte Carlo (QMC) calculations were shown to be useful methods to recover correlation in NaK, essential to obtain a reasonable description of the molecule. The equilibrium distance—interpolated from the potential energy curves—yield a value of 3.5 Å, in agreement with the experimental value. The dissociation energy, however, is not as good. In this case, a conventional CCSD(T) calculation with an extended aug-pc-4 basis set gives a much better agreement to experiment. On the contrary, the CCSD(T), other MO and DFT methods are not able to reproduce correctly the large dipole moment of this molecule. Even DMC methods with a simple HF trial wavefunction are able to give a better agreement to experiment. RMC methods are even better, and the value obtained with a B3LYP trial wavefunction is very close to the experimental one.</p>

scholarly journals Investigation of Some Antiviral N-Heterocycles as COVID 19 Drug: Molecular Docking and DFT Calculations

2020 ◽  
Vol 21 (11) ◽  
pp. 3922 ◽  
Author(s):  
Mohamed Hagar ◽  
Hoda A. Ahmed ◽  
Ghadah Aljohani ◽  
Omaima A. Alhaddad
Keyword(s):  
Dipole Moment ◽  
Molecular Docking ◽  
Dft Calculations ◽  
Binding Affinity ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Hydrophobic Interactions ◽  
Chemical Reactivity ◽  
Main Protease

The novel coronavirus, COVID-19, caused by SARS-CoV-2, is a global health pandemic that started in December 2019. The effective drug target among coronaviruses is the main protease Mpro, because of its essential role in processing the polyproteins that are translated from the viral RNA. In this study, the bioactivity of some selected heterocyclic drugs named Favipiravir (1), Amodiaquine (2), 2′-Fluoro-2′-deoxycytidine (3), and Ribavirin (4) was evaluated as inhibitors and nucleotide analogues for COVID-19 using computational modeling strategies. The density functional theory (DFT) calculations were performed to estimate the thermal parameters, dipole moment, polarizability, and molecular electrostatic potential of the present drugs; additionally, Mulliken atomic charges of the drugs as well as the chemical reactivity descriptors were investigated. The nominated drugs were docked on SARS-CoV-2 main protease (PDB: 6LU7) to evaluate the binding affinity of these drugs. Besides, the computations data of DFT the docking simulation studies was predicted that the Amodiaquine (2) has the least binding energy (−7.77 Kcal/mol) and might serve as a good inhibitor to SARS-CoV-2 comparable with the approved medicines, hydroxychloroquine, and remdesivir which have binding affinity −6.06 and −4.96 Kcal/mol, respectively. The high binding affinity of 2 was attributed to the presence of three hydrogen bonds along with different hydrophobic interactions between the drug and the critical amino acids residues of the receptor. Finally, the estimated molecular electrostatic potential results by DFT were used to illustrate the molecular docking findings. The DFT calculations showed that drug 2 has the highest of lying HOMO, electrophilicity index, basicity, and dipole moment. All these parameters could share with different extent to significantly affect the binding affinity of these drugs with the active protein sites.

Structural polymorphism of pyrazinium hydrogen sulfate: extending chemistry of the pyrazinium salts with small anions

2010 ◽  
Vol 66 (4) ◽  
pp. 451-457 ◽  
Author(s):  
Armand Budzianowski ◽  
Mariana Derzsi ◽  
Piotr J. Leszczyński ◽  
Michał K. Cyrański ◽  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Dipole Moment ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Density Functional ◽  
Hydrogen Sulfate ◽  
Structural Polymorphism ◽  
Functional Theory ◽  
First Time

Two polymorphs (α, β) of pyrazinium hydrogen sulfate (pyzH+HSO_4^-, abbreviated as PHS) with distinctly different hydrogen-bond types and topologies but close electronic energies have been synthesized and characterized for the first time. The α-polymorph (P212121) forms distinct blocks in which the pyzH+ and HSO_4^- ions are interconnected through a network of NH...O and OH...O hydrogen bonds. The β-form (P\bar 1) consists of infinite chains of alternating pyzH+ and HSO_4^- ions connected by NH...O and OH...N hydrogen bonds. Density functional theory (DFT) calculations indicate the possible existence of a hypothetical polar P1 form of the β-polymorph with an unusually high dipole moment.

Unusual effects of solvent polarity on capacitance for organic electrolytes in a nanoporous electrode

Nanoscale ◽  
2014 ◽  
Vol 6 (10) ◽  
pp. 5545-5550 ◽  
Author(s):  
De-en Jiang ◽  
Jianzhong Wu
Keyword(s):  
Density Functional Theory ◽  
Dipole Moment ◽  
Density Functional ◽  
Solvent Polarity ◽  
Density Functional Theory Calculations ◽  
Organic Electrolyte ◽  
Functional Theory ◽  
Organic Electrolytes

Classical density functional theory calculations suggest that there is an optimal dipole moment for the solvent in an organic electrolyte supercapacitor.

THEORETICAL CHARACTERS OF MgX (X = Te, Se, S AND O) CLUSTERS

2010 ◽  
Vol 19 (04) ◽  
pp. 695-701 ◽  
Author(s):  
SHUHONG XU ◽  
CHUNLEI WANG ◽  
YIPING CUI
Keyword(s):  
Dipole Moment ◽  
Absorption Spectra ◽  
Raman Spectra ◽  
Density Functional ◽  
Nbo Analysis ◽  
Time Dependent ◽  
Theoretical Level ◽  
Functional Theory ◽  
Regular Change ◽  
Water As Solvent

At DFT/B3LYP/LANL2DZ theoretical level, a series of MgX clusters with Mg3X3 hexagon, Mg4X4-t tetrahedron and Mg4X4-o octagon conformations are investigated. Their wavelengths of absorption spectra are calculated with time-dependent Density Functional Theory (TDDFT) using water as solvent. Firstly, the lowest vibrational frequencies, bond lengths, Dipole Moment and Raman spectra of them present regular change. Dipole Moment result shows that different clusters have different charges. From Raman spectra, we have discovered that they correlate with the conformation and variety of clusters. Conformations of MgO clusters have different optimizing characters with MgS , MgSe and MgTe molecules. Secondly, through Molecular Orbital and Nature Bond Orbital (NBO) analysis, we have found that all these clusters are materials with wider gaps. MgTe structures have stronger bonding. Besides, MgO have different transition from the other clusters. The order of wavelengths of absorption spectra is MgTe > MgSe > MgS . In a word, except MgO molecules, these clusters have similar or regular characters. These results are significant for experimental study of MgX nanocrystals.

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