Comparação Entre Métodos Para Determinação De Cargas Atômicas Em Sistemas Moleculares: A Molécula N-{N-(Pterina-7-Il)carbonilglicil}-L-Tirosina (Nnpt)

Botelho, Fernanda D.; Oliveira, Roberta Siqueira Soldaini; Almeida, Joyce S. F. D. de; França, Tanos C. C.; Borges, Itamar

doi:10.21577/0100-4042.20170683

Cited by 5 publications

(10 citation statements)

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“…Despite this particularity of the Hirshfeld method, recent studies have concluded that it accurately predicts regioselectivity in electrophilic aromatic substitution reactions, the energy of hydrogen bonds between methane molecules, and the charges of atoms in covalent bonds, among other relevant chemical properties. 49 Our results here indicate also the same behavior concerning Hammett's constants.…”

Section: Atomic Charge Methodssupporting

confidence: 85%

“…Despite its low computational cost, Mulliken charges suffer from two major problems: (i) the electronic density between two atoms is equally divided between them, regardless of the electronegativity; and (ii) the method employs a set of non-orthogonal basis set that can lead to undesired results. 49 Löwdin atomic charges 47,48 are an improvement over Mulliken charges because it forms orthogonal basis sets by applying symmetric transformations on all orbitals, hence eliminating the overlap partitions which solves the aforementioned problem (ii). Löwdin charges also have the advantage over Mulliken charges of being less dependent on the size of the basis set.…”

Section: Atomic Charge Methodsmentioning

confidence: 99%

“…The major difference between the Chelp and ChelpG methods is that the ChelpG process uses an algorithm based on regularly spaced points to make point selections. 49 This algorithm differs from the original Chelp program since it was found that it was not invariant to coordinate rotations and internal bond rotations, among other properties. 54…”

Section: Atomic Charge Methodsmentioning

confidence: 99%

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Machine learning determination of new Hammett's constants for meta- and para-substituted benzoic acid derivatives employing quantum chemical atomic charge methods

Monteiro-de-Castro

Duarte

Borges

2023

Preprint

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Hammett's constants quantify the electron or electron acceptor power of a chemical group bonded to an aromatic ring. Their experimental values have been successfully used in a large variety of applications, but some of them may have inconsistent values or were not measured. For this reason, developing an accurate and consistent set of Hammett's values is paramount. In this work, we employed the machine learning (ML) regression algorithms Decision Tree Regressor, the neural network Multilayer Perceptron Regressor, and Lasso Lars IC in a cross-validation (CV) approach combined with quantum chemical calculations of atomic charges to estimate theoretically the new Hammett's constants for 90 chemical donor or acceptor groups by employing different types of quantum chemical atomic charges of the groups as input properties. New 219 sigma values, including previously unknown ones, are proposed for 90 chemical donor or acceptor groups by employing different types of quantum chemical atomic charges of the groups as input properties. The different substituent groups were bonded to benzene and meta- and para-substituted benzoic acid derivatives. Among the investigated atomic charge methods (Mulliken, Lwdin, Hirshfeld, and ChelpG), Hirshfeld's method showed the best regressions for most of the different kinds of sigma values. For each type of Hammett constant, linear expressions depending only on the atomic charges of the group were obtained. Correlation coefficients as high as 0.945, mean squared errors (MSE) as low as 0.004, and root mean square errors (RMSE) as low 0.062, were found. The ML approach, in most cases, showed very close predictions to the original experimental values, with the values from meta- and para-substituted benzoic acid derivatives showing the most accurate values. A new consistent set of Hammetts constants is presented, as well as simple equations for predicting new values for groups not included in the original set of 90.

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Section: Atomic Charge Methodssupporting

confidence: 85%

Section: Atomic Charge Methodsmentioning

confidence: 99%

Section: Atomic Charge Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Machine learning determination of new Hammett's constants for meta- and para-substituted benzoic acid derivatives employing quantum chemical atomic charge methods

Monteiro-de-Castro

Duarte

Borges

2023

Preprint

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“…Although this method is an improvement over Mulliken’s, there is a general agreement in the literature that the charges calculated using the Hirshfeld method typically are very small, close to zero. − This is true since the weighting factor is evaluated so that the molecule’s atom is considered to be very similar to the isolated atom. Despite this particularity of the Hirshfeld method, recent studies have concluded that it accurately predicts regioselectivity in electrophilic aromatic substitution reactions, the energy of hydrogen bonds between methane molecules, and the charges of atoms in covalent bonds, among other relevant chemical properties . Our results here also indicate the same behavior concerning Hammett’s constants.…”

Section: Methodssupporting

confidence: 74%

“…In this method, the expansion coefficients are taken from the Hartree–Fock (HF) variational method, and the electronic population is separated according to the atomic orbital (AO) contributions. Despite its low computational cost, Mulliken charges suffer from two major problems: (i) the electronic density between two atoms is equally divided, regardless of the electronegativity and (ii) the method employs a set of non-orthogonal basis set that can lead to undesired results …”

Section: Methodsmentioning

confidence: 99%

Machine Learning Determination of New Hammett’s Constants for meta- and para-Substituted Benzoic Acid Derivatives Employing Quantum Chemical Atomic Charge Methods

2023

Self Cite

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Hammett's constants σ quantify the electron donor or electron acceptor power of a chemical group bonded to an aromatic ring. Their experimental values have been successfully used in many applications, but some are inconsistent or not measured. Therefore, developing an accurate and consistent set of Hammett's values is paramount. In this work,we employed different types of machine learning (ML) algorithms combined with quantum chemical calculations of atomic charges to predict theoretically new Hammett's constants σ m , σ p , σ m 0 , σ p 0 , σ p + , σ p − , σ R , and σ I for 90 chemical donor or acceptor groups. New σ values (219), including previously unknown 92, are proposed. The substituent groups were bonded to benzene and meta-and para-substituted benzoic acid derivatives. Among the charge methods (Mulliken, Loẅdin, Hirshfeld, and ChelpG), Hirshfeld showed the best agreement for most kinds of σ values. For each type of Hammett constant, linear expressions depending on carbon charges were obtained. The ML approach overall showed very close predictions to the original experimental values, with meta-and para-substituted benzoic acid derivative values showing the most accurate values. A new consistent set of Hammett's constants is presented, as well as simple equations for predicting new values for groups not included in the original set of 90.

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The effect of the electronic structure method and basis set on the accuracy of the electric multipoles computed with the distributed multipole analysis (DMA)

Oliveira,

Borges

2023

J Mol Model

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Context An accurate description of the molecular charge density is crucial for investigating intraand inter-molecular properties. Among the different ways of describing and analyzing it, the widely used distributed multipole analysis (DMA) is an accurate method for decomposing the molecular charge density into atom-centered electric multipoles (monopole, dipole, quadrupole, and so on) that have a direct chemical interpretation. In this work, DMA was employed to decompose the molecular charge density of six chemically distinct molecules, namely, (2R)-2amino-3-[(S)-prop-2-enylsulfinyl] propanoic acid (AAP), 4-amine-2-nitro-1,3,5 triazole (ANTA), (RS)-Propan-2-yl methylphosphonofluoridate (SARIN), chloromethane (CLMET) and 2-aminoacetic acid (GLY) into monopole, dipole, and quadrupole values. A hypothetical variation of ANTA built by exchanging all the nitrogen atoms with phosphorus that we named 4-phosphine-2-phosphite-1,3,5-phosphorine (ANTAP) was also studied. These molecules have different chemical structures bearing distinct carbon skeletons, electronegative atoms, and electronwithdrawing/donating groups. We found that although DFT multipole values can depend considerably on the exchange-correlation functional for specific atomic sites, the associated rootmean-square errors (RMSE) compared to benchmark MP4 mainly were about 10 −5 . The most significant variations were for monopoles and dipoles of sites highly polarized by adjacent atoms, and to a lesser degree, for the quadrupoles. The double hybrid B2PLYP and the hybrid meta M06-2X functionals, as expected in the framework of Jacob's ladder, overall give the most accurate results among the DFT methods. The MP2 DMA multipole values have an RMSE in relation to the MP4 benchmark mainly in the range 10 −4 − 10 −6 , thus representing a lower computational cost to obtain results with similar good accuracy without the ambiguity of choosing a DFT functional. The deviations of the HF multipoles from the benchmark in most cases were less than 20%, in agreement with the well-known fact that non-correlated charge densities have a slight dependence on the electronic correlation. We also confirmed that DMA values have a small dependence on the size of the basis set: deviations did not exceed 5% in most cases. However, the dependence of the DMA values on the size of the basis set increases with the rank of the electric multipole. To compute accurate values of DMA multipoles of an atom bonded to very electronegative atoms, especially dipoles (a measure of polarization) and quadrupoles (a measure of electron delocalization), a large basis set including diffuse functions is necessary. Despite that, for a given polarized basis set, the choice of the basis set to compute accurate DMA multipole values is not critical. MethodsThe molecular charge densities were computed using the electronic structure methods Hartree-Fock (HF), MP2, MP4, DFT/PBE, DFT/B3LYP, DFT/B3PW91, DFT/M06-2X, and DFT/B2PLYP implemented in the Gaussian 09 package. MP4 was the benchmark method. The DMA multipoles...

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Comparação Entre Métodos Para Determinação De Cargas Atômicas Em Sistemas Moleculares: A Molécula N-{N-(Pterina-7-Il)carbonilglicil}-L-Tirosina (Nnpt)

Cited by 5 publications

References 0 publications

Machine learning determination of new Hammett's constants for meta- and para-substituted benzoic acid derivatives employing quantum chemical atomic charge methods

Machine learning determination of new Hammett's constants for meta- and para-substituted benzoic acid derivatives employing quantum chemical atomic charge methods

Machine Learning Determination of New Hammett’s Constants for meta- and para-Substituted Benzoic Acid Derivatives Employing Quantum Chemical Atomic Charge Methods

The effect of the electronic structure method and basis set on the accuracy of the electric multipoles computed with the distributed multipole analysis (DMA)

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