Popular Electronic Structure Principles in a Dynamical Context

Chattaraj, Pratim Kumar; Sengupta, S.

doi:10.1021/jp961096f

Cited by 361 publications

(239 citation statements)

References 52 publications

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“…Hardness (g) has been defined within the DFT as the second derivative of the E with respect to N at tðrÞ property which measures both the stability and reactivity of a molecule [82][83][84][85][86][87][88][89][90].…”

Section: Calculation Methodsmentioning

confidence: 99%

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Ebenso

Arslan

Kandemi̇rlı

et al. 2010

Int J of Quantum Chemistry

149

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Density functional theory (DFT) at the B3LYP/6-31G (d,p) and BP86/ CEP-31G* basis set levels and ab initio calculations using the RHF/6-31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely E HOMO (highest occupied molecular orbital energy), E LUMO (lowest unoccupied molecular orbital energy), the energy gap (DE), the Mulliken charges on the C, O, N, S atoms, hardness (g), softness (S), polarizability (a), dipole moment (l), total energy change (DE T ), electrophilicity (x), electron affinity (A), ionization potential (I), the absolute electronegativity (v), and the fraction of electrons transferred (DN). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the E HOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism.

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Section: Calculation Methodsmentioning

confidence: 99%

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Ebenso

Arslan

Kandemi̇rlı

et al. 2010

Int J of Quantum Chemistry

149

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“…In this last group one can make a distinction between the principles based on general quantum theory, for instance, the Hückel rule, 4 the Woodward-Hoffmann rules, 5 and the maximum molecular valence principle, 6 and those that are rooted in the density functional theory ͑DFT͒, such as the Sanderson electronegativity equalization principle ͑EEP͒, 7 the hard-soft acid-base principle ͑HSAB͒, 8,9 the maximum hardness principle ͑MHP͒, [9][10][11] and minimum polarizability principle ͑MPP͒. 12,13 Actually, the MHP and MPP principles are among the most widely accepted electronic structure principles of chemical reactivity. The MHP affirms that, at a given temperature, molecular systems evolve to a state of maximum hardness.…”

Section: Introductionmentioning

confidence: 99%

Are the maximum hardness and minimum polarizability principles always obeyed in nontotally symmetric vibrations?

Torrent‐Sucarrat

Luis

Duran

et al. 2002

The Journal of Chemical Physics

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In a recent paper ͓J. Am. Chem. Soc. 123, 7951 ͑2001͔͒ we have shown for the first time the existence of molecules with nontotally symmetric vibrational modes that break the maximum hardness ͑MHP͒ and minimum polarizability ͑MPP͒ principles. We present here an extension of this previous work by devising a mathematical procedure that helps to determine the nontotally symmetric molecular distortions of a given molecule that do not follow the MPP or the MHP. This methodology is based on the diagonalization of the Hessian matrix of the polarizability or the hardness with respect to the vibrational normal coordinates. For a relatively large series of molecules, we have carried out diagonalizations of the Hessian matrix of the polarizability to determine the molecular distortions with a more marked MPP or anti-MPP character. From the results obtained, we have derived a set of simple rules that allow to predict a priori without calculations the existence of vibrational modes that break the MPP. With respect to the MHP, the results strongly depend on the method of calculation, but the same rules are useful to predict the existence of vibrational modes that disobey the MHP when the Koopmans' approximation is used to calculate the hardness.

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“…During molecule formation the electronegativities of the pertinent atoms get equalized [42,43]. A stable configuration or a favorable process is generally associated with maximum hardness [36,37], minimum polarizability [44][45][46][47] and maximum entropy [48] values. The conditions for maximum hardness and entropy and minimum polarizability complement the usual minimum energy criterion for stability.…”

Section: Introductionmentioning

confidence: 99%

“…A molecular reaction dynamics can be envisaged [44] by monitoring the time evolution of the electronegativity of a specific atom from its isolated atom value to the equalized molecular electronegativity value as well as by studying the dynamic profiles of hardness and entropy and how they get maximized and that of the minimization of polarizability during the course of the chemical reaction. In the present work we study the interaction of a hydrogen atom in its ground electronic state and an excited electronic state with laser fields of different colors.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chemical Reactivity Dynamics and Quantum Chaos in Highly Excited Hydrogen Atoms in an External Field: A Quantum Potential Approach

Chattaraj

Maiti

2002

IJMS

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Dynamical behavior of chemical reactivity indices like electronegativity, hardness, polarizability, electrophilicity and nucleophilicity indices is studied within a quantum fluid density functional framework for the interactions of a hydrogen atom in its ground electronic state (n = 1) and an excited electronic state (n = 20) with monochromatic and bichromatic laser pulses. Time dependent analogues of various electronic structure principles like the principles of electronegativity equalization, maximum hardness, minimum polarizability and maximum entropy have been found to be operative. Insights into the variation of intensities of the generated higher order harmonics on the color of the external laser field are obtained. The quantum signature of chaos in hydrogen atom has been studied using a quantum theory of motion and quantum fluid dynamics. A hydrogen atom in the electronic ground state (n = 1) and in an excited electronic state ( n = 20) behaves differently when placed in external oscillating monochromatic and bichromatic electric fields. Temporal evolutions of Shannon entropy, quantum Lyapunov exponent and Kolmogorov -Sinai entropy defined in terms of the distance between two initially close Bohmian trajectories for these two cases show marked differences. It appears that a larger uncertainty product and a smaller hardness value signal a chaotic behavior.

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Popular Electronic Structure Principles in a Dynamical Context

Cited by 361 publications

References 52 publications

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Are the maximum hardness and minimum polarizability principles always obeyed in nontotally symmetric vibrations?

Chemical Reactivity Dynamics and Quantum Chaos in Highly Excited Hydrogen Atoms in an External Field: A Quantum Potential Approach

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