Solvent Effects. 5. Influence of Cavity Shape, Truncation of Electrostatics, and Electron Correlation on ab Initio Reaction Field Calculations

1996 ◽  
Vol 100 (40) ◽  
pp. 16098-16104 ◽  
Author(s):  
James B. Foresman ◽  
Todd A. Keith ◽  
Kenneth B. Wiberg ◽  
John Snoonian ◽  
Michael J. Frisch
Keyword(s):  
Ab Initio ◽  
Solvent Effects ◽  
Electron Correlation ◽  
Cavity Shape ◽  
Reaction Field

scholarly journals A Combined Synthetic and DFT Study on the Catalyst-Free and Solvent-Assisted Synthesis of 1,3,4-Oxadiazole-2-thiol Derivatives

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mohammad Soleiman-Beigi ◽  
Reza Aryan ◽  
Maryam Yousofizadeh ◽  
Shima Khosravi
Keyword(s):  
Field Theory ◽  
Ab Initio ◽  
Solvent Effects ◽  
Reaction Medium ◽  
Theoretical Studies ◽  
Product Selectivity ◽  
Efficient Catalyst ◽  
Reaction Field ◽  
Effect Of Solvents ◽  
Catalyst Free

A novel practical and efficient catalyst-free method for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols has been developed, which is assisted by reaction solvent (DMF). The solvent effects on product selectivity were studied based on Onsager’s reaction field theory of electrostatic solvation. The ab initio theoretical studies on the effect of solvents on the process also supported the suitability of DMF as the reaction medium for the preparation of 1,3,4-oxadiazole-2-thiol derivatives.

An ab initio study of the H2O-mediated 1,3-hydrogen rearrangement in the isoelectric series: X, Y = CH2, NH, or O

1991 ◽  
Vol 69 (10) ◽  
pp. 1589-1599 ◽  
Author(s):  
Raymond A. Poirier ◽  
Dake Yu ◽  
Peter R. Surjan
Keyword(s):  
Ab Initio ◽  
Solvent Effects ◽  
Basis Set ◽  
Correlation Effects ◽  
Ab Initio Study ◽  
Reaction Field ◽  
Effect Of Solvent ◽  
Isoelectronic Series ◽  
Intramolecular Hydrogen ◽  
Hydrogen Rearrangement

Ab initio calculations are performed to investigate the effect of water on the 1,3-intramolecular hydrogen rearrangement in the [Formula: see text] isoelectronic series, for X, Y = CH2, NH or O, by modeling with a single H2O molecule. The geometries for the complexes are optimized at both the 3-21G and 6-31G** basis set levels. MP2 and some MP4 calculations are performed to take into account the correlation effects, and ZPV corrections are calculated at the MNDO level. The results show that the water molecule has a significant effect on the molecules in which hydrogen bonds can be formed or partially formed. The "solvent effects" are also examined using the self-consistent reaction-field (SCRF) approach. A combination of supermolecule and SCRF approach appears to work well at predicting the effect of solvent on relative stabilities and barriers. Key words: tautomerism, ab initio, 1,3-hydrogen rearrangement, solvent effects.

Quantifying electron-correlation effects in small coinage-metal clusters by ab initio calculations

2021 ◽  
Author(s):  
Victor Giovanni de Pina ◽  
Bráulio Gabriel Alencar Brito ◽  
Guo -Q Hai ◽  
Ladir Cândido
Keyword(s):  
Monte Carlo ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Metal Clusters ◽  
Correlation Effects ◽  
Diffusion Monte Carlo ◽  
Coinage Metal ◽  
Electron Correlation Effects ◽  
Fixed Node

We investigate many-electron correlation effects in neutral and charged coinage-metal clusters Cun, Agn, and Aun (n = 1 − 4) by ab initio calculations using fixed-node diffusion Monte Carlo (FN-DMC)...

Solvent and temperature effects on the tautomerization of a carbonitrile molecule: A conductor-like polarizable continuum model (CPCM) study

2021 ◽  
Vol 20 (1) ◽  
pp. 59-68
Author(s):  
Zohreh Khanjari ◽  
Bita Mohtat ◽  
Reza Ghiasi ◽  
Hoorieh Djahaniani ◽  
Farahnaz Kargar Behbahani
Keyword(s):  
Gas Phase ◽  
Solvent Effects ◽  
Continuum Model ◽  
Solvent Polarity ◽  
Polarizable Continuum Model ◽  
Dielectric Constants ◽  
Frontier Orbitals ◽  
Reaction Field ◽  
Polarizable Continuum ◽  
Homo Lumo

This research examined the effects of solvent polarity and temperature on the tautomerization of a carbonitrile molecule at CAM-B3LYP/6-311G (d,p) level of theory. The selected solvents were n-hexane, diethyl ether, pyridine, ethanol, methanol, and water. The solvent effects were examined by the self-consistent reaction field theory (SCRF) based on conductor-like polarizable continuum model (CPCM). The solvent effects were explored on the energy barrier, frontier orbitals energies, and HOMO-LUMO gap. Dependencies of thermodynamic parameters (ΔG and ΔH) on the dielectric constants of solvents were also tested. Specifically, the temperature dependencies of the thermodynamics parameters were studied within 100–1000 K range. The rate constant of the tautomerism reaction was computed from 300 to 1200 K, in the gas phase.

Ab initio calculation of [OH−;e+] system with consideration of electron correlation effect

1994 ◽  
Vol 101 (7) ◽  
pp. 5925-5928 ◽  
Author(s):  
Masanori Tachikawa ◽  
Hiroshi Sainowo ◽  
Kaoru Iguchi ◽  
Kazunari Suzuki
Keyword(s):  
Ab Initio ◽  
Electron Correlation ◽  
Ab Initio Calculation ◽  
Correlation Effect ◽  
Electron Correlation Effect

scholarly journals An ab initio study on the insertion reactions of CH [X2II] with NH3, H2O, and HF

1996 ◽  
Vol 74 (6) ◽  
pp. 910-917 ◽  
Author(s):  
Zhi-Xiang Wang ◽  
Ruo-Zhuang Liu ◽  
Ming-Bao Huang ◽  
Zhonghua Yu
Keyword(s):  
Ab Initio ◽  
Electron Correlation ◽  
Lower Energy ◽  
Energy Surface ◽  
Molecular Orbital Calculations ◽  
Ab Initio Study ◽  
Insertion Reactions ◽  
Moller Plesset ◽  
Ch Radical ◽  
Water Hydrogen

The mechanisms of the reactions of CH (X2II) with NH3, H2O, and HF have been studied by means of ab initio molecular orbital calculations incorporating electron correlation with Møller–Plesset perturbation theory up to the second order. For each of the three CH reactions, the insertion path has been found in the potential energy surface; in the calculated insertion path there exists an intermediate complex prior to the transition state that has a lower energy than the reactants. Energetic results indicate that insertion paths are favourable channels for these CH reactions, which is in line with proposals based on kinetic experiments. Key words: CH radical, ammonia, water, hydrogen fluoride, reaction mechanism.

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