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Kaan C. Emregül - One of the best experts on this subject based on the ideXlab platform.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
E J Baerends - One of the best experts on this subject based on the ideXlab platform.
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on derivatives of the Energy with respect to total electron number and Orbital occupation numbers a critique of janak s theorem
Molecular Physics, 2020Co-Authors: E J BaerendsAbstract:The relation between the derivative of the Energy with respect to occupation number and the Orbital Energy, ∂E/∂ni=ϵi, was first introduced by Slater for approximate total Energy expressions such a...
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the kohn sham gap the fundamental gap and the optical gap the physical meaning of occupied and virtual kohn sham Orbital energies
Physical Chemistry Chemical Physics, 2013Co-Authors: O V Gritsenko, E J Baerends, R Van Der MeerAbstract:A number of consequences of the presence of the exchange–correlation hole potential in the Kohn–Sham potential are elucidated. One consequence is that the HOMO–LUMO Orbital Energy difference in the KS-DFT model (the KS gap) is not “underestimated” or even “wrong”, but that it is physically expected to be an approximation to the excitation Energy if electrons and holes are close, and numerically proves to be so rather accurately. It is physically not an approximation to the difference between ionization Energy and electron affinity I − A (fundamental gap or chemical hardness) and also numerically differs considerably from this quantity. The KS virtual Orbitals do not possess the notorious diffuseness of the Hartree–Fock virtual Orbitals, they often describe excited states much more closely as simple Orbital transitions. The Hartree–Fock model does yield an approximation to I − A as the HOMO–LUMO Orbital Energy difference (in Koopmans' frozen Orbital approximation), if the anion is bound, which is often not the case. We stress the spurious nature of HF LUMOs if the Orbital Energy is positive. One may prefer Hartree–Fock, or mix Hartree–Fock and (approximate) KS operators to obtain a HOMO–LUMO gap as a Koopmans' approximation to I − A (in cases where A exists). That is a different one-electron model, which exists in its own right. But it is not an “improvement” of the KS model, it necessarily deteriorates the (approximate) excitation Energy property of the KS gap in molecules, and deteriorates the good shape of the KS virtual Orbitals.
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asymptotic correction of the exchange correlation kernel of time dependent density functional theory for long range charge transfer excitations
Journal of Chemical Physics, 2004Co-Authors: O V Gritsenko, E J BaerendsAbstract:Time-dependent density functional theory (TDDFT) calculations of charge-transfer excitation energies ωCT are significantly in error when the adiabatic local density approximation (ALDA) is employed for the exchange–correlation kernel fxc. We relate the error to the physical meaning of the Orbital Energy of the Kohn–Sham lowest unoccupied molecular Orbital (LUMO). The LUMO Orbital Energy in Kohn–Sham DFT—in contrast to the Hartree–Fock model—approximates an excited electron, which is correct for excitations in compact molecules. In CT transitions the Energy of the LUMO of the acceptor molecule should instead describe an added electron, i.e., approximate the electron affinity. To obtain a contribution that compensates for the difference, a specific divergence of fxc is required in rigorous TDDFT, and a suitable asymptotically correct form of the kernel fxcasymp is proposed. The importance of the asymptotic correction of fxc is demonstrated with the calculation of ωCT(R) for the prototype diatomic system HeB...
O V Gritsenko - One of the best experts on this subject based on the ideXlab platform.
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charge transfer ct Orbitals for the one electron description of ct excitations in a wide range of donor acceptor separations
Chemical Physics Letters, 2017Co-Authors: O V GritsenkoAbstract:A transformation of the virtual Kohn-Sham Orbitals is proposed to a set of charge-transfer Orbitals (CTOs) adapted to description of CT excitations. The CTO scheme offers a simple estimate of the CT excitation Energy with an Orbital Energy difference. This estimate reproduces well the reference values of the configuration interaction (CI) method in a wide range of donor-acceptor separations in the paradigmatic He-Be complex. CTO-based Orbital Energy and shape indices are proposed to assess the suitability of the CT description with virtual Orbitals of a given basis set. Both indices yield correct trends for the Kohn-Sham and Hartree-Fock Orbitals.
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the kohn sham gap the fundamental gap and the optical gap the physical meaning of occupied and virtual kohn sham Orbital energies
Physical Chemistry Chemical Physics, 2013Co-Authors: O V Gritsenko, E J Baerends, R Van Der MeerAbstract:A number of consequences of the presence of the exchange–correlation hole potential in the Kohn–Sham potential are elucidated. One consequence is that the HOMO–LUMO Orbital Energy difference in the KS-DFT model (the KS gap) is not “underestimated” or even “wrong”, but that it is physically expected to be an approximation to the excitation Energy if electrons and holes are close, and numerically proves to be so rather accurately. It is physically not an approximation to the difference between ionization Energy and electron affinity I − A (fundamental gap or chemical hardness) and also numerically differs considerably from this quantity. The KS virtual Orbitals do not possess the notorious diffuseness of the Hartree–Fock virtual Orbitals, they often describe excited states much more closely as simple Orbital transitions. The Hartree–Fock model does yield an approximation to I − A as the HOMO–LUMO Orbital Energy difference (in Koopmans' frozen Orbital approximation), if the anion is bound, which is often not the case. We stress the spurious nature of HF LUMOs if the Orbital Energy is positive. One may prefer Hartree–Fock, or mix Hartree–Fock and (approximate) KS operators to obtain a HOMO–LUMO gap as a Koopmans' approximation to I − A (in cases where A exists). That is a different one-electron model, which exists in its own right. But it is not an “improvement” of the KS model, it necessarily deteriorates the (approximate) excitation Energy property of the KS gap in molecules, and deteriorates the good shape of the KS virtual Orbitals.
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asymptotic correction of the exchange correlation kernel of time dependent density functional theory for long range charge transfer excitations
Journal of Chemical Physics, 2004Co-Authors: O V Gritsenko, E J BaerendsAbstract:Time-dependent density functional theory (TDDFT) calculations of charge-transfer excitation energies ωCT are significantly in error when the adiabatic local density approximation (ALDA) is employed for the exchange–correlation kernel fxc. We relate the error to the physical meaning of the Orbital Energy of the Kohn–Sham lowest unoccupied molecular Orbital (LUMO). The LUMO Orbital Energy in Kohn–Sham DFT—in contrast to the Hartree–Fock model—approximates an excited electron, which is correct for excitations in compact molecules. In CT transitions the Energy of the LUMO of the acceptor molecule should instead describe an added electron, i.e., approximate the electron affinity. To obtain a contribution that compensates for the difference, a specific divergence of fxc is required in rigorous TDDFT, and a suitable asymptotically correct form of the kernel fxcasymp is proposed. The importance of the asymptotic correction of fxc is demonstrated with the calculation of ωCT(R) for the prototype diatomic system HeB...
Nurdane Yilmaz - One of the best experts on this subject based on the ideXlab platform.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
Ymit Ergun - One of the best experts on this subject based on the ideXlab platform.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
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a combined electrochemical and theoretical study into the effect of 2 thiazole 2 ylimino methyl phenol as a corrosion inhibitor for mild steel in a highly acidic environment
Corrosion Science, 2016Co-Authors: Nurdane Yilmaz, Alper Fitoz, Ymit Ergun, Kaan C. EmregülAbstract:Abstract 2-((Thiazole-2-ylimino)methyl)phenol (THYMP) was studied as a corrosion inhibitor for the protection of mild steel in 2 M HCl solution by means of weight loss, polarization, electrochemical impedance spectroscopy and scanning electron microscopy. The potential of zero charge (E pzc ), was also determined for evaluation of the adsorption mechanism. Quantum chemical parameters such as highest occupied molecular Orbital Energy (E HOMO ), lowest unoccupied molecular Orbital Energy (E LUMO ), Energy gap (οE), dipole moment (μ) etc. were calculated using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Theoretical and experimental results were in fairly good agreement.
