Extended-basis-set rpae calculations of molecular photoionization cross sections: theoretical studies of Vπ-Vσ interaction in molecular nitrogen

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

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The Calculations of Dipole Polarizabilities and Anisotropies by the CNDO Method: The Effect of an Extended-basis Set

Bulletin of the Chemical Society of Japan ◽

10.1246/bcsj.48.3431 ◽

1975 ◽

Vol 48 (12) ◽

pp. 3431-3435 ◽

Cited By ~ 28

Author(s):

Hiroyuki Shinoda ◽

Tatsuo Akutagawa

Keyword(s):

Basis Set ◽

Cndo Method ◽

Extended Basis ◽

Dipole Polarizabilities

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Net charges and valence AO's in the methylamines; the hydrogen basis set and the properties of nitrogen

Canadian Journal of Chemistry ◽

10.1139/v85-255 ◽

1985 ◽

Vol 63 (7) ◽

pp. 1487-1491 ◽

Cited By ~ 9

Author(s):

Giuseppe Del Re ◽

Sándor Fliszár ◽

Michel Comeau ◽

Claude Mijoule

Keyword(s):

Basis Set ◽

Basis Sets ◽

Methyl Groups ◽

Extended Form ◽

Amine Nitrogen ◽

Methyl Group ◽

Net Charges ◽

Extended Basis

Net charges and valence AO's for ammonia, methylamine, dimethylamine, and trimethylamine were calculated using extended basis sets. Superposition effects, evaluated by replacing Pople's standard 6-31G* basis by an extended form in which the basis of the ammonia H atoms and of the methyl groups of trimethylamine are retained in the treatment of each molecule, indicate that the quality of the treatment of amine nitrogen atoms is strongly dependent on the number of methyl groups. A new, augmented basis is proposed for the hydrogens, which appears to be reasonably well balanced: comparison with familiar (e.g., 6-31G*) calculations illustrates in what manner the treatment of nitrogen is worsened when even just one methyl group is replaced by hydrogen unless the impoverishment of the basis is suitably taken care of.

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Deformation distortions of geometric form tube blanks in the process of drilling holes

10.36652/1813-1336-2021-17-3-104-110 ◽

2021 ◽

pp. 104-110

Author(s):

A.N. Isaev ◽

S.V. Vlaskin ◽

V.A. Lebedev ◽

M.D. Gavrilenko

Keyword(s):

Stress State ◽

Wall Thickness ◽

Cross Sections ◽

Theoretical Studies ◽

Geometric Form ◽

Axisymmetric Stress ◽

Axisymmetric Stress State ◽

Elastic Plastic ◽

The Cross

The influence of deviations of the shape of the cross-sections of pipes from roundness on the axisymmetric stress state and taking this factor into account in theoretical studies and methods for solving problems of mandrel drilling in the elastic-plastic mode are considered. The features of the choice of tubular blanks, which help to reduce the unevenness of deformation and increase the accuracy of processing in the process of mandrel drilling, are revealed. Recommendations are given for eliminating the variance in wall thickness of blanks at the stage of their preparation for the mandrel operation.

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Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2451 ◽

2021 ◽

Vol 507 (4) ◽

pp. 5264-5271

Author(s):

Manel Naouai ◽

Abdelhak Jrad ◽

Ayda Badri ◽

Faouzi Najar

Keyword(s):

Inelastic Scattering ◽

Total Energy ◽

Cross Sections ◽

Three Dimensional ◽

Basis Set ◽

Rate Coefficients ◽

Close Coupling ◽

Explicitly Correlated ◽

Correlation Consistent ◽

Triple Excitation

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

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Etude théorique de la structure et de la réactivité de l'anion du pentazole

Canadian Journal of Chemistry ◽

10.1139/v83-251 ◽

1983 ◽

Vol 61 (7) ◽

pp. 1435-1439 ◽

Cited By ~ 29

Author(s):

Minh-Tho Nguyen ◽

Michel Sana ◽

Georges Leroy ◽

Jose Elguero

Keyword(s):

Molecular Nitrogen ◽

Activation Energies ◽

Basis Set ◽

Etude Théorique ◽

Mo Calculations ◽

Étude Théorique ◽

Azide Ion ◽

Synthetic Target ◽

Stable Structures

"Abinitio" LCAO-SCF-MO calculations using the 4-31G basis set were carried out in order to study the supersystem [Formula: see text]. The three possible stable structures (azide ion + molecular nitrogen, pentazene ion, and pentazole ion) and their reactions paths were calculated. The pentazole anion is less stable than the reagents [Formula: see text], but much more stable than the pentazene anion; it could constitute a reasonable synthetic target. The activation energies of the different paths were compared with those of the neutral supersystem N5H.

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