scholarly journals Charge Density Analysis and Transport Properties of TTF Based Molecular Nanowires: A DFT Approach

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Karuppannan Selvaraju ◽  
Poomani Kumaradhas
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Electron Density ◽  
Quantum Chemical ◽  
Molecular Conformation ◽  
Topological Analysis ◽  
Basis Set ◽  
Bond Critical Point ◽  
Chemical Calculation ◽  
Energy Density Distribution

The present study has been performed to understand the charge density distribution and the electrical characteristics of Au and thiol substituted tetrathiafulvalene (TTF) based molecular nanowire. A quantum chemical calculation has been carried out using DFT method (B3LYP) with the LANL2DZ basis set under various applied electric fields (EFs). The bond topological analysis characterizes the terminal Au–S and S–C bonds as well as all the bonds of central TTF unit of the molecule. The variation of electron density and Laplacian of electron density at the bond critical point of bonds for zero and different applied fields reveal the electron density distribution of the molecule. The molecular conformation, the variation of atomic charges and energy density distribution of the molecule have been analyzed for the various levels of applied EFs. The HOMO-LUMO gap calculated from quantum chemical calculations has been compared with the value calculated from the density of states. The variation of dipole moment due to the polarization effect and the I-V characteristics of the molecule for the various applied EFs have been well discussed.

Structure and charge density distribution of amine azide based hypergolic propellant molecules: a theoretical study

2016 ◽  
Vol 94 (2) ◽  
pp. 126-136 ◽  
Author(s):  
Gopal Kandhakumar ◽  
Chinnasamy Kalaiarasi ◽  
Poomani Kumaradhas
Keyword(s):  
Energy Density ◽  
Density Distribution ◽  
Charge Density ◽  
Electron Density ◽  
Density Functional ◽  
Density Functional Method ◽  
Basis Set ◽  
Chemical Calculation ◽  
Azide Group ◽  
Energy Density Distribution

A quantum chemical calculation and charge density analysis of some amine azide based propellants (DMAZ, DMAEH, ADMCPA, AMCBA and ACPA) have been carried out to understand the geometry, bond topological, electrostatic, and energetic properties. The topological properties of electron density of the molecules were determined using Bader’s theory of atoms in molecules from the wave functions obtained from the density functional method (B3LYP) with the 6-311G** basis set. The electron density distribution of these molecules reveals the nature of chemical bonding in the molecules. The azide group attached C−N bonds of all molecules exhibit the electron density of ρbcp(r) ∼1.639 e Å−3 and the Laplacian of electron density ∇2ρbcp(r) is ∼–14.0 e Å−5, in which the corresponding values of the ADMCPA molecule are relatively high, 1.725 e Å–3 and –15.2 e Å−5 respectively, whereas for the methylamine group attached C–N bonds, these values are found to be higher (1.824 e Å–3 and –17.25 e Å−5). The Laplacian of terminal N–N bonds of the azide group is highly negative, indicating that these charges are highly concentrated, whereas the charge concentration of the dimethylamine group attached N–N bond of DMEAH is very much less, confirming that the bond is the weakest bond among the molecules. The energy density has been calculated for each bond of the molecules, which insights the energy density distribution of the molecules. Relatively, the molecules exhibit distinct electrostatic properties that are related to different charge distribution in the molecules. Large negative electrostatic potential regions are found at the vicinity of the amine and azide groups of the molecules. The charge imbalance parameter of the molecules has been determined and shows that the DMAEH molecule is the least sensitive molecule in this series.

Topological analysis of electron density and the electrostatic properties of isoniazid: an experimental and theoretical study

2014 ◽  
Vol 70 (2) ◽  
pp. 331-341 ◽  
Author(s):  
Gnanasekaran Rajalakshmi ◽  
Venkatesha R. Hathwar ◽  
Poomani Kumaradhas
Keyword(s):  
Hydrogen Bonding ◽  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Bond Critical Point ◽  
Potential Region ◽  
Electrostatic Properties ◽  
Structural And Electronic Properties ◽  
Density Analysis ◽  
Mycobacterial Cell Wall

Isoniazid (isonicotinohydrazide) is an important first-line antitubercular drug that targets the InhA enzyme which synthesizes the critical component of the mycobacterial cell wall. An experimental charge-density analysis of isoniazid has been performed to understand its structural and electronic properties in the solid state. A high-resolution single-crystal X-ray intensity data has been collected at 90 K. An aspherical multipole refinement was carried out to explore the topological and electrostatic properties of the isoniazid molecule. The experimental results were compared with the theoretical charge-density calculations performed usingCRYSTAL09with the B3LYP/6-31G** method. A topological analysis of the electron density reveals that the Laplacian of electron density of the N—N bond is significantly less negative, which indicates that the charges at the b.c.p. (bond-critical point) of the bond are least accumulated, and so the bond is considered to be weak. As expected, a strong negative electrostatic potential region is present in the vicinity of the O1, N1 and N3 atoms, which are the reactive locations of the molecule. The C—H...N, C—H...O and N—H...N types of intermolecular hydrogen-bonding interactions stabilize the crystal structure. The topological analysis of the electron density on hydrogen bonding shows the strength of intermolecular interactions.

Experimental and theoretical charge density, intermolecular interactions and electrostatic properties of metronidazole

2019 ◽  
Vol 75 (6) ◽  
pp. 942-953 ◽  
Author(s):  
Chinnasamy Kalaiarasi ◽  
Christy George ◽  
Rajesh G. Gonnade ◽  
Venkatesha R. Hathwar ◽  
Kumaradhas Poomani
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Intermolecular Interactions ◽  
Topological Analysis ◽  
Intramolecular Hydrogen Bonding ◽  
Bond Critical Point ◽  
Monoclinic System ◽  
Electrostatic Properties ◽  
Negative Laplacian ◽  
Intramolecular Hydrogen

Metronidazole is a radiosensitizer; it crystallizes in the monoclinic system with space group P21/c. The crystal structure of metronidazole has been determined from high-resolution X-ray diffraction measurements at 90 K with a resolution of (sin θ/λ)max = 1.12 Å−1. To understand the charge-density distribution and the electrostatic properties of metronidazole, a multipole model refinement was carried out using the Hansen–Coppens multipole formalism. The topological analysis of the electron density of metronidazole was performed using Bader's quantum theory of atoms in molecules to determine the electron density and the Laplacian of the electron density at the bond critical point of the molecule. The experimental results have been compared with the corresponding periodic theoretical calculation performed at the B3LYP/6-31G** level using CRYSTAL09. The topological analysis reveals that the N—O and C—NO2 exhibit less electron density as well as negative Laplacian of electron density. The molecular packing of crystal is stabilized by weak and strong inter- and intramolecular hydrogen bonding and H...H interactions. The topological analysis of O—H...N, C—H...O and H...H intra- and intermolecular interactions was also carried out. The electrostatic potential of metronidazole, calculated from the experiment, predicts the possible electrophilic and nucleophilic sites of the molecule; notably, the hydroxyl and the nitro groups exhibit large electronegative regions. The results have been compared with the corresponding theoretical results.

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

Nonnuclear Maxima in the Charge Density

1993 ◽  
Vol 48 (1-2) ◽  
pp. 127-133 ◽  
Author(s):  
Kenneth E. Edgecombe ◽  
Vedene H. Smith, Jr. ◽  
Florian Müller-Plathe
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Electron Correlation ◽  
Basis Set ◽  
Valence Shell ◽  
Correlation Effects ◽  
Electron Correlation Effects

Abstract Basis-set and electron-correlation effects on the appearance and disappearance of nonnuclear maxima in the electron density are examined in Li2 , Na2 , Na4 and Na5 . It is shown that nonnuclear attractors can be removed in all cases except Li2 . The appearance of a pseudoatom in a lithium molecule correlates remarkably well with the size of the region, in an atomic calculation, of V2r(r) for the valence shell of the atom. This and the fact that the pseudoatom is also present in the promolecule indicate that the pseudoatoms are remnants of, or in fact are portions of, atoms that are not perturbed enough in the molecule to remove an essentially atomic characteristic.

scholarly journals Geometric and energetic data from quantum chemical calculations of halobenzenes and xylenes

2020 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Software Package ◽  
Geometry Optimization ◽  
Theoretical Data ◽  
Basis Set ◽  
Chemical Calculation ◽  
Custom Made

<p>This article presents theoretical data on geometric and energetic features of halobenzenes and xylenes. Data were obtained from <i>ab initio</i> geometry optimization and frequency calculations at HF, B3LYP, MP2 and CCSD levels of theory on 6-311++G(d,p) basis set. In total, 1504 structures of halobenzenes, three structures of xylenes and one structure of benzene were generated and processed by custom-made codes in Mathematica. The quantum chemical calculation was completed in Q-Chem software package. Geometric and energetic data of the compounds are presented in this paper as supplementary tables. Raw output files as well as codes and scripts associated with production and extraction of data are also provided.</p>

Theoretical investigation of the stability, reactivity, and the interaction of methyl-substituted peridinium-based ionic liquids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Emmanuel A. Bisong ◽  
Hitler Louis ◽  
Tomsmith O. Unimuke ◽  
Victoria M. Bassey ◽  
John A. Agwupuye ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Electron Density ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Stabilization Energy ◽  
Basis Set ◽  
Bond Critical Point ◽  
Electronic Interaction ◽  
Donor And Acceptor ◽  
The Stability

Abstract This research work focuses on the reactivity, stability, and electronic interaction of pyridinium hydrogen nitrate (PHN)-based ionic liquids and the influence of methyl substituent on this class of ionic liquids: Ortho- (O-MPHN), meta- (M-MPHN), and para- (P-MPHN) substitution. Natural bond orbital (NBO) calculations were performed at the density functional theory (DFT) with Becke’s Lee Yang and Parr functional (B3LYP) methods and DFT/B3LYP/6-311++G(d,p) as basis set using GAUSSIAN 09W and GAUSSVIEW 6.0 software and the most important interaction between donor (Filled Lewis-type NBO’s) and the acceptor (vacant non-Lewis NBOs) were observed. From our natural bond orbital (NBO) result, it could be deduced that the higher the stabilization energy value, the greater the interaction between the donor and acceptor NBOs. The stability of the studied compounds is said to follow the order from O-MPHN > PHN > P-MPHN > M-MPHN based on the hyperconjugative interaction (stabilization energy) of the most significant interaction. The result of the highest occupied molecular orbital (HOMO), shows that PHN has the highest HOMO while the substituted derivatives have similar HOMO values between −7.70 and −7.98 eV thus PHN complex is the best electron donor while the substituted derivatives act as electron acceptors due to the presence of methyl group substituent which is observed to be electron deficient as a result of its withdrawal effect from the aromatic ring. Furthermore, the electron density, real space functions such as energy density and Laplacian of electron density at bond critical point (BCP) of the hydrogen bond interaction of the studied compounds were analyzed using Multifunctional Wavefunction analyzer software version 3.7 and it was observed that the hydrogen at position 6 and oxygen at position 11 (H6–O11) of M-methyl pyridinium nitrate with bond distance of 4.59 (Å) gave binding energy with the strongest electrostatic interaction between the cation and anion of the compounds under investigation. We also observed from our results that, substitution at the ortho position enhances the stability and strengthen the extent of charge transfer. This therefore implies that substitution at ortho position is more favorable for inter- and intramolecular interactions resulting to stabilization of the studied molecules.

Sign in / Sign up

Export Citation Format

Share Document