Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO/ClOX Isomers (X = H, O, and Cl) Using DFT and CCSD(T) Methods

Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO Isomers (X=H,O,Cl) Using DFT and CCSD(T) Methods

10.26434/chemrxiv.6135389 ◽

2018 ◽

Author(s):

Oscar Ventura ◽

Kenneth Irving ◽

Martina Kieninger

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Enthalpies Of Formation ◽

Isodesmic Reactions ◽

Dft Methods ◽

Functional Methods ◽

The One ◽

Isomeric Structures ◽

Different Sources

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species as well as the two isomeric structures XClO/ClOX for each X=H, Cl and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK and B2PLYP functionals. Geometry optimizations as well as reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n=2-6. For the calculation of enthalpies of formation, atomization as well as isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3 and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations, and the most accurate derived theoretically up to present. Different sources of error in the calculations are discussed in detail.

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Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO Isomers (X=H,O,Cl) Using DFT and CCSD(T) Methods

10.26434/chemrxiv.6135389.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Oscar Ventura ◽

Kenneth Irving ◽

Martina Kieninger

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Enthalpies Of Formation ◽

Isodesmic Reactions ◽

Dft Methods ◽

Functional Methods ◽

The One ◽

Isomeric Structures ◽

Different Sources

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species as well as the two isomeric structures XClO/ClOX for each X=H, Cl and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK and B2PLYP functionals. Geometry optimizations as well as reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n=2-6. For the calculation of enthalpies of formation, atomization as well as isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3 and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations, and the most accurate derived theoretically up to present. Different sources of error in the calculations are discussed in detail.

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COMPARATIVE QUANTUM STUDY ON TERT-BUTYL RADICAL AND CATION

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633611006487 ◽

2011 ◽

Vol 10 (03) ◽

pp. 325-348 ◽

Cited By ~ 4

Author(s):

ANNA IGNACZAK

Keyword(s):

Density Functional ◽

Structural Parameters ◽

Coupling Constants ◽

Basis Set ◽

Basis Sets ◽

Inversion Barrier ◽

Gaussian Basis Sets ◽

Dft Methods ◽

Tert Butyl ◽

Butyl Radical

Detailed comparative analysis of properties of the tert-butyl radical and cation is performed using 14 density functional (DFT) methods combined with double-zeta and triple-zeta quality Gaussian basis sets with polarization and diffuse functions. Stability of different conformers is discussed. Structural parameters, dipole moment, adiabatic ionization potential (IP), inversion barrier and isotropic hyperfine coupling constants are examined and compared to values obtained at the standard MP2 level and to experimental data available. All methods indicate that that the CC bond in the radical is longer than in the cation by about 0.033 Å. The IP values are found to be very sensitive to the method used and range from 612 to 709 kJ/mol, but majority oscillate around 646÷656 kJ/mol. Calculated inversion barrier for the radical is higher than the experimental estimate of 2.68 kJ/mol; with the 6-311++G** basis set and most DFT methods it is predicted in the range 3.86÷4.82 kJ/mol. All DFT methods predict for the out-of-plane CC3 bending mode of the radical the frequency around 260 cm-1, while in the cation the corresponding frequency is higher by about 180 cm-1.

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A DFT INVESTIGATION ON BASIS SET SIZE AND HYDROGEN-BONDING EFFECTS ON 17O AND 2H NQR PARAMETERS

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633613500223 ◽

2013 ◽

Vol 12 (04) ◽

pp. 1350022 ◽

Cited By ~ 1

Author(s):

MEHDI D. ESRAFILI ◽

NAFISEH MOHAMMADIRAD

Keyword(s):

Density Functional ◽

Quadrupole Coupling Constant ◽

Basis Set ◽

Basis Sets ◽

Coupling Constant ◽

Dft Methods ◽

Functional Theory ◽

Set Size ◽

Quadrupole Coupling ◽

Consistent Basis

A systematic theoretical study on various maleic acid (MA) clusters has been carried out employing density functional theory (DFT) methods. The performance of two different functionals namely B3LYP and M06 in the prediction of geometries, 17 O and 2 H nuclei quadrupole coupling constant (CQ) values of the MA clusters has been assessed comparing the results to those experimental data. For DFT calculations, several basis sets have been used, including the recently developed Jensen's polarization-consistent basis set families, pcJ-n and pcS-n (n = 0,1,2,3). Calculations at the basis set limit indicate that the value of CQ(2 H ) in monomer MA, changes by 0.01–0.04 kHz for each of the final two basis set increments, and seems reasonable to conclusion that the pcJ-3 result is within a few kHz of the basis set limit. Convergence with respect to basis set size was found to be very good, and the pcJ-1 and pcS-1 basis sets provided a good compromise between the basis set limit and computational expense. In most cases, the differences between B3LYP and M06 results for a given basis set are in a range of 1–2%. On the other hand, no systematic changes in the CQ(17 O ) or CQ(2 H ) were found for basis sets larger than double-ζ. Thus, the usual assumption that double-ζ basis set (pcJ-1 and pcS-1) results in the acceptable CQ values, seems to be valid in the case of 17 O and 2 H nuclei.

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Chemically Accurate Excitation Energies With Small Basis Sets

10.26434/chemrxiv.8427116.v1 ◽

2019 ◽

Author(s):

Emmanuel Giner ◽

Anthony Scemama ◽

Julien Toulouse ◽

Pierre-Francois Loos

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Density Functional ◽

Chem Phys ◽

Basis Set ◽

Basis Sets ◽

Excitation Energies ◽

Functional Correction ◽

The One ◽

Range Density

By combining extrapolated selected configuration interaction (sCI) energies obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) algorithm with the recently proposed short-range density-functional correction for basis-set incompleteness [Giner et al., J. Chem. Phys. 2018, 149, 194301], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-ζ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer and ethylene). The present study clearly evidences that special care has to be taken with very diffuse excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.

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THEORETICAL EVALUATION OF THE pKa VALUES OF 5-SUBSTITUED URACIL DERIVATIVES

Vietnam Journal of Science and Technology ◽

10.15625/2525-2518/55/6a/12365 ◽

2018 ◽

Vol 55 (6A) ◽

pp. 63

Author(s):

Pham Le Nhan ◽

Nguyen Tien Trung

Keyword(s):

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Stable Form ◽

Dft Methods ◽

Theoretical Evaluation ◽

Pka Values ◽

Uracil Derivatives ◽

Solvation Energies ◽

Gaussian Basis Set

Density functional theory (DFT) calculations using numerical basis sets were employed to predict the solvation energies, Gibbs free energies and pKa values of a series of 5-substituted uracil derivatives. Obtained results show that solvation energies are not significantly different between DFT methods using the numerical (DNP) and Gaussian basis set (aug-cc-pVTZ). It is noteworthy that the independent and suitable solvation energy of proton of -258.6 kcal/mol has been proposed for the evaluation of pKa values in conjunction with the numerical basis set. In addition, the calculated pKa values suggest that the anti-conformation of 5-formyluracil is the most stable form in the aqueous solution.

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THEORETICAL CHARACTERIZATION OF A HIGHLY ELECTROPHILIC CARBENE

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633605001854 ◽

2005 ◽

Vol 04 (03) ◽

pp. 823-832 ◽

Cited By ~ 5

Author(s):

JUAN F. VAN DER MAELEN URÍA ◽

JAVIER RUIZ ◽

SANTIAGO GARCÍA-GRANDA

Keyword(s):

Density Functional ◽

Theoretical Calculations ◽

Basis Set ◽

Basis Sets ◽

Singlet Ground State ◽

X Ray Diffraction ◽

Dft Methods ◽

Hartree Fock ◽

Experimental Complex ◽

Experimental Geometry

The experimental geometry obtained from single-crystal X-ray diffraction data for a metalladiphosphanyl carbene precursor is compared with the results of theoretical calculations made at the ab initio level by using Hartree–Fock (HF) and Density Functional Theory (DFT) methods over the carbene itself. Theoretical geometry optimizations for the singlet ground state of [ Mn(CO)4(PH2)2C: ]+ have been performed with several hybrid functionals and basis sets. Calculated geometries showed a perfect C 2v symmetry in the highest levels of calculation and were somewhat relaxed when compared with the experimental ones; for instance, with the largest basis set, the P–C–P angle found was 124.8°, whereas C–P bond distances were both 1.667 Å, compared to 103.5(3)° and 1.718(5) Å, respectively, from the experimental data. The absence of a ligand attached to the C : atom in the calculated structure, which is present in the form of iodine in the experimental complex, is probably responsible, to a certain extent, for the discrepancies. In addition to the structural computations, in order to theoretically quantify the highly electrophilic character expected for the carbene, electron affinities were calculated and found to be between 6.24 eV and 6.97 eV at different DFT levels of calculation, which confirmed the expectations. In this respect, a comparison with the analogous [Ru(CNH)4(PH2)2C:]2+ carbene is also made, showing the possibility of experimentally trapping the manganese carbene.

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Interaction of Several Toxic Heterocarbonyl Gases with Polypyrrole as a Potential Gas Sensor

Chemosensors ◽

10.3390/chemosensors8030084 ◽

2020 ◽

Vol 8 (3) ◽

pp. 84

Author(s):

Francisco C. Franco

Keyword(s):

Gas Sensor ◽

Density Functional ◽

Energy Gap ◽

Carbonyl Sulfide ◽

High Sensitivity ◽

Basis Sets ◽

Dft Methods ◽

Functional Methods ◽

Sensitivity And Selectivity ◽

High Level

The interactions of the toxic heterocarbonyl gases phosgene, carbonyl fluoride, formaldehyde, carbonyl sulfide, and acetone with polypyrrole as a toxic heterocarbonyl gas sensor, were extensively studied by density functional theory (DFT). The Becke 3-parameter, Lee-Yang-Parr (B3LYP) exchange-correlation functional methods were first tested against several high-level DFT methods employing the Dunning’s double-ζ and triple-ζ basis sets and were found to be sufficient in describing the non-covalent interactions involved in this study. The interaction of pyrrole with the heterocarbonyl gases resulted in changes in the structure and optoelectronic properties of the polymer and it was observed that acetone and formaldehyde had the strongest H-bonding interaction with polypyrrole, while the interaction of phosgene and formaldehyde resulted in the lowest energy gap and may result in its high sensitivity towards these gases. The UV-Vis absorption revealed significant red-shifted first singlet excited states (Eexcited, 1st) of the complexes and follows the same trend as the EGap values. It is shown that the Eexcited, 1st was due to the π(HOMOPy) ⟶ π*(LUMOHC) transitions and the excited state at maximum absorption (Eexcited, max) was due to the π(HOMOPy) ⟶ π*(LUMOPy) transitions. This study demonstrates the potential sensitivity and selectivity of polypyrrole as a toxic heterocarbonyl sensor.

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Assessing the performance of commonly used DFT functionals in studying the chemistry of frustrated Lewis pairs

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633613500740 ◽

2014 ◽

Vol 13 (01) ◽

pp. 1350074 ◽

Cited By ~ 15

Author(s):

Fang Huang ◽

Jinliang Jiang ◽

Mingwei Wen ◽

Zhi-Xiang Wang

Keyword(s):

Lewis Acids ◽

Density Functional ◽

Basis Set ◽

Basis Sets ◽

Frustrated Lewis Pairs ◽

Dft Methods ◽

Functional Theory ◽

Donor Acceptor ◽

Reaction Barriers ◽

Better Than

The benchmark study has assessed the performance of 18 density functional theory (DFT) functionals, including GGAs, hybrid-GGAs, meta-GGAs, and hybrid meta-GGAs, in predicting bonding strength, barrier height and structure for systems involving Lewis acids and bases. Three databases were built for the study, including 15 bonding enthalpies of dative bonds (DBH15), 10 reaction barriers (BH10) and 10 X-ray structures (XCS10). Wavefunction-based ab initio calculations were also carried out for comparisons. The benchmark data were computed at the CCSD(T)/BSI//MP2/BSI(BSI=aug-cc-pVTZ) level. The 6-311++G(d,p)(BSII) and 6-31G(d,p)(BSIII) basis sets were employed in DFT calculations. Generally, M06-2X/BSII and M05-2X/BSII outperform the other tested DFT methods. M05-2X/BSIII and M06-2X/BSIII are less accurate than M05-2X/BSII and M06-2X/BSII (or M05-2X/BSII//M05-2X/BSIII and M06-2X/BSII//M06-2X/BSIII), suggesting that large basis sets (e.g. BSII) are necessary to improve energetics. SCS-MP2 is less accurate than MP2, consistently overestimating bonding enthalpies and reaction barriers. Moreover, six DFT functionals (M05-2X, M06-2X, B3LYP, ωB97X-D, BMK and B97-D) were examined by comparing with the experimental bonding enthalpies of eighteen donor–acceptor complexes, which indicate that M05-2X and M06-2X are still better than others. Nevertheless, M05-2X and M06-2X significantly overestimate or underestimate the bonding enthalpies of F-substituted complexes, implying the necessity of improving the two functionals for describing fluorides. Using the six basis sets (BSI, cc-pVTZ, aug-cc-pVDZ, cc-pVDZ, TZVP and BSII) and DBH15 and BH10 databases, the influence of the basis sets on the performance of M06-2X functional was examined, which reveals that BSII is the most suitable basis set for the functional.

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Chemically Accurate Excitation Energies With Small Basis Sets

10.26434/chemrxiv.8427116 ◽

2019 ◽

Author(s):

Emmanuel Giner ◽

Anthony Scemama ◽

Julien Toulouse ◽

Pierre-Francois Loos

Keyword(s):

Excited States ◽

Configuration Interaction ◽

Density Functional ◽

Chem Phys ◽

Basis Set ◽

Basis Sets ◽

Excitation Energies ◽

Functional Correction ◽

The One ◽

Range Density

By combining extrapolated selected configuration interaction (sCI) energies obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) algorithm with the recently proposed short-range density-functional correction for basis-set incompleteness [Giner et al., J. Chem. Phys. 2018, 149, 194301], we show that one can get chemically accurate vertical and adiabatic excitation energies with, typically, augmented double-ζ basis sets. We illustrate the present approach on various types of excited states (valence, Rydberg, and double excitations) in several small organic molecules (methylene, water, ammonia, carbon dimer and ethylene). The present study clearly evidences that special care has to be taken with very diffuse excited states where the present correction does not catch the radial incompleteness of the one-electron basis set.

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