Theoretical atomic radii of elements (H-Cm): A non-relativistic study with Gaussian basis set using HF, post-HF and DFT methods

<div><p>We calculated the most probable radius of an atom for elements from H to Cm. The calculations were carried out by using non-relativistic, spin polarized, HF, MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated with the experimental first ionization energies. This non-relativistic atomic radii were also compared with other theoretical atomic radii. With respect to the Dirac-Slater data, our values were in good agreement with the elements up to Sn. Relationship with van der Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div>

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Theoretical Atomic Radii of Elements (H-Cm): A Non-Relativistic Study with Gaussian Basis Set Using HF, Post-HF and DFT Methods

10.26434/chemrxiv.13663337.v1 ◽

2021 ◽

Author(s):

Krishnamohan Prasanna ◽

Sooraj Sunil ◽

Ajith Kumar ◽

Jamesh Joseph

Keyword(s):

Electron Correlation ◽

Van Der Waals ◽

Basis Set ◽

Dft Methods ◽

Ionization Energies ◽

Spin Polarized ◽

Gaussian Basis Set ◽

Van Der Waals Radii ◽

Atomic Radii ◽

Good Agreement

<div><p>We calculated the most probable radius of an atom for elements from H to Cm. The calculations were carried out by using non-relativistic, spin polarized, HF, MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated with the experimental first ionization energies. This non-relativistic atomic radii were also compared with other theoretical atomic radii. With respect to the Dirac-Slater data, our values were in good agreement with the elements up to Sn. Relationship with van der Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div>

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Conformational Structure of Chloromethyldichlorophosphines

Zeitschrift für Naturforschung A ◽

10.1515/zna-2002-6-708 ◽

2002 ◽

Vol 57 (6-7) ◽

pp. 333-336

Author(s):

Evgenii A. Romanenko ◽

Alexander M. Nesterenko

Keyword(s):

Experimental Data ◽

Ab Initio Calculations ◽

Ab Initio ◽

Electron Correlation ◽

Basis Set ◽

Conformational Structure ◽

Gauche Conformation ◽

Nuclear Quadrupole ◽

Set Up ◽

Good Agreement

IThe 35Cl nuclear quadrupole resonances (77 K) and ab initio calculations of trichloromethyldichlorophosphine () show that it exists in the chess conformation form. The barrier to internal rotation about the P-C bond in I at the RHF/6-31++ G(d,p) level equals to 38.1 kJ mol-1. In chloromethyldichlorophosphine (II) the extension of the basis set up to the RHF/6-311++G(df, pd) level does not improve the description of the most preferable gauche-conformation; only if electron correlation (at the MP2 level) is taken into account the results are in a good agreement with experimental data.

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Universal Gaussian basis functions in relativistic quantum chemistry: atomic Dirac–Fock–Coulomb and Dirac–Fock–Breit calculations

Canadian Journal of Chemistry ◽

10.1139/v92-225 ◽

1992 ◽

Vol 70 (6) ◽

pp. 1822-1826 ◽

Cited By ~ 13

Author(s):

G. L. Malli ◽

A. B. F. Da Silva ◽

Yasuyuki Ishikawa

Keyword(s):

Relativistic Quantum ◽

Basis Set ◽

Basis Sets ◽

Interaction Energies ◽

Gaussian Basis Sets ◽

Consistent Field ◽

Self Consistent ◽

Self Consistent Field ◽

Gaussian Basis Set ◽

Good Agreement

Matrix Dirac–Fock–Coulomb and Dirac–Fock–Breit self-consistent field calculations are performed for a number of neutral atoms. He (Z = 2) through Xe (Z = 54), using the universal Gaussian basis set (18s, 12p, 11d) reported recently by Da Silva etal. The total Dirac–Fock–Coulomb, the Dirac–Fock–Breit, and the Breit interaction energies calculated with this universal Gaussian basis set are in good agreement with the corresponding values obtained by using an extensive well-tempered Gaussian basis set for the He through Ca (Z = 20) atoms. Although this universal Gaussian basis set is inadequate for the calculation of total Dirac–Fock–Coulomb and Dirac–Fock–Breit energies for the Kr, Sr, and Xe atoms, the Breit interaction energies calculated with this basis for these three atoms are in very good agreement with the corresponding Breit interaction energies obtained by using the extensive well-tempered Gaussian basis sets. Work is in progress to generate a more extensive and energetically better universal Gaussian basis set for He through Xe for its use in non-relativistic Hartree–Fock as well as Dirac–Fock self-consistent field calculations on polyatomics involving heavy atoms.

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van der Waals Radii of Noble Gases

Inorganic Chemistry ◽

10.1021/ic501364h ◽

2014 ◽

Vol 53 (17) ◽

pp. 9260-9266 ◽

Cited By ~ 27

Author(s):

Jürgen Vogt ◽

Santiago Alvarez

Keyword(s):

Noble Gases ◽

Van Der Waals ◽

Van Der Waals Radii

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Crystal structure and DFT computational studies of (E)-2,4-di-tert-butyl-6-{[3-(trifluoromethyl)benzyl]iminomethyl}phenol

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s205698902000537x ◽

2020 ◽

Vol 76 (5) ◽

pp. 732-735

Author(s):

Nihal Kan Kaynar ◽

Hasan Tanak ◽

Mustafa Macit ◽

Namık Özdemir

Keyword(s):

Molecular Structure ◽

Crystal Structure ◽

Density Functional ◽

Basis Set ◽

Aromatic Rings ◽

Dft Methods ◽

Functional Theory ◽

Compound C ◽

Potential Map ◽

Good Agreement

The title compound, C23H28F3NO, is an ortho-hydroxy Schiff base compound, which adopts the enol–imine tautomeric form in the solid state. The molecular structure is not planar and the dihedral angle between the planes of the aromatic rings is 85.52 (10)°. The trifluoromethyl group shows rotational disorder over two sites, with occupancies of 0.798 (6) and 0.202 (6). An intramolecular O—H...N hydrogen bonding generates an S(6) ring motif. The crystal structure is consolidated by C—H...π interactions. The molecular structure was optimized via density functional theory (DFT) methods with the B3LYP functional and LanL2DZ basis set. The theoretical structure is in good agreement with the experimental data. The frontier orbitals and molecular electrostatic potential map were also examined by DFT computations.

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Estudo cinético da abstração do hidrogênio do acetato de metila

10.21826/viiiseedmol202040 ◽

2020 ◽

Author(s):

Leandro da Silva Pereira ◽

Leonardo Baptista

Keyword(s):

Transition State Theory ◽

Methyl Esters ◽

Hydrogen Abstraction ◽

State Theory ◽

Basis Set ◽

Rate Coefficients ◽

Dft Methods ◽

Carbon Chains ◽

Kinetics Of ◽

Good Agreement

Biodiesel is a fuel formed by methyl esters with large carbon chains. The investigation of the hydrogen abstraction reactions of small methyl esters can be helpful to the improvement and development of kinetics models of biodiesel combustion. For this reason, the present study aims to study the thermochemistry and kinetics of hydrogen abstraction of methyl ethanoate using DFT methods and transition state theory. The abstraction reactions by O2, O, HO2, and H were studied with the B3LYP-D3 and M06-2X functionals with cc-pVDZ, ccpVTZ, aug-cc-pVDZ, and aug-cc-pVTZ basis set. At 298 K, the rate coefficients evaluated are in good agreement with the literature’s coefficients and the faster reaction occurs in the presence of O atoms. The hydrogen abstraction by O2 molecule it is not important at 298 K, but should be included in the present study since it should be important at higher temperatures.

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Theoretical Study of Reaction Between Nitrilimine and 1,4 Oxazine 2 Carboxylate by MP2 and DFT Methods

Oriental Journal Of Chemistry ◽

10.13005/ojc/340640 ◽

2018 ◽

Vol 34 (6) ◽

pp. 2992-2997

Author(s):

H. El-Hadki ◽

F. Hlimi ◽

M. Salah ◽

K. Marakchi ◽

N. Komiha ◽

...

Keyword(s):

Energy Surface ◽

Theoretical Study ◽

Basis Set ◽

Dft Methods ◽

Reactivity Indices ◽

B3lyp Method ◽

Transition Structures ◽

Potential Energy Surface Calculation ◽

Good Agreement ◽

Surface Calculation

The regioselectivity of the reaction between phenyldiazen-1-ium-1-ylidene p-tolyl methanide and ethyl 4-benzoyl-4H-benzo [1,4]oxazine-2-carboxylate were studied by means of the DFT/B3LYP method coupled by the 6-31g(d) basis and MP2 in connection with 6-31G(d) and 6-31G+(d,p) basis set. The mechanism of this regioselectif reaction has performed by transition state optimization, evaluation of the potential energy surface, calculation of IRC and reactivity indices. Location and verification of minima and transition structures have been realized by using the Berny's algorithm. The process of formation of the two regioisomers is achieved through concerted and asynchronous mechanism. The results are in good agreement with the experimental data.

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Theoretical Study on the Static (Hyper)Polarizabilities of α-t-Bu-ω-CN-Poly(methylphenyl)silane

Advances in Physical Chemistry ◽

10.1155/2013/905910 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8

Author(s):

Jing Li ◽

Liang Peng ◽

Feng Long Gu

Keyword(s):

Electron Correlation ◽

Conjugated Polymer ◽

Main Chain ◽

Theoretical Study ◽

Correlation Effect ◽

Basis Set ◽

Electron Correlation Effect ◽

Hartree Fock ◽

Linear And Nonlinear ◽

Good Agreement

The static linear and nonlinear optical properties of the σ-conjugated polymer α-t-Bu-ω-CN-poly(methylphenyl)silane (PMS) are studied at the Coupled-Perturbed Hartree-Fock (CPHF) level with 6-31+G(d) basis set. The calculated results reveal that the static first hyperpolarizabilities of this system increase with the main chain length and have a good agreement with experiments. The (hyper)polarizabilities per unit cell have been extrapolated to infinite chain limit and a comparison is made to those of polysilane and polyacetylene (PA). Besides, other structural properties depending on the σ-conjugated Si–Si skeleton length are investigated as well. Electron correlation effect is estimated and it turns out that the MP2 static first hyperpolarizability is about times larger than the corresponding CPHF value for the polymer with .

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Correction to van der Waals Radii of Noble Gases

Inorganic Chemistry ◽

10.1021/ic502140y ◽

2014 ◽

Vol 53 (19) ◽

pp. 10779-10779

Author(s):

Jürgen Vogt ◽

Santiago Alvarez

Keyword(s):

Noble Gases ◽

Van Der Waals ◽

Van Der Waals Radii

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