نتایج جستجو برای: b3lyp calculations

تعداد نتایج: 113771  

Journal: :Acta chimica Slovenica 2013
Nader Zabarjad Shiraz Elaheh Sadat Sharifzadeh Neda Koosha

In this study electrophilic affinities were calculated at all reactive positions of azulene in electrophilic aromatic substitutions. Structures of cationic intermediates and products were optimized at HF/6-31+G* and B3LYP/6-31+G** levels of theory, and single point calculations were carried out at MP2/6-31+G**//B3LYP/6-31+G** for total energy. NICS calculations, activation energies and relative...

Journal: :Journal of computational chemistry 2003
Marcus Elstner Qiang Cui Petra Munih Efthimios Kaxiras Thomas Frauenheim Martin Karplus

Parameters for the zinc ion have been developed in the self-consistent charge density functional tight-binding (SCC-DFTB) framework. The approach was tested against B3LYP calculations for a range of systems, including small molecules that contain the typical coordination environment of zinc in biological systems (cysteine, histidine, glutamic/aspartic acids, and water) and active site models fo...

Journal: :Molecules 2008
Iwona Kowalczyk

1,1-Dimethyl-3-oxo-1,4-diazepan-1-ium chloride (1) and 1,1-dimethyl-1-carboxymethyl-3-aminopropyl ammonium hydrochloride (2) have been obtained by the reactions of 1,1-dimethyl-1,3-propylenediamine with ethyl chloroacetate and chloroacetic acid, respectively. The products have been characterized by FTIR, Raman and NMR spectroscopy. B3LYP calculations have also been carried out. The screening co...

Journal: :Organic & biomolecular chemistry 2011
Luis Simón Jonathan M Goodman

There have been many comparisons of computational methods applied to ground states, but studies of organic reactions usually require calculations on transition states, and these provide a different test of the methods. We present calculations of the geometries of nineteen covalent-bond forming transition states using HF and twelve different functionals, including GGA, hybrid-GGA and hybrid meta...

Journal: :International Journal of Advanced Engineering Research and Science 2017

2015
Guo-bing Wang Hui-qing Zhao Zhen-lin Zhang Wen-lou Wang Dong-ming Chen

The B state excited resonance Raman scattering of tetraoxaporphyrin dication (TOP) was theoretically studied with DFT/TDDFT calculations and the sum-over-states approach of polarizability including both the A and B terms contributions. The resonance Raman spectra calculated with PBE1PBE, B3LYP, Cam-B3LYP, and B3LYP-D3 functionals are similar to each other in general, with PBE1PBE and B3LYP bein...

Journal: :Physical chemistry chemical physics : PCCP 2015
Rebecca A Coates Christopher P McNary Georgia C Boles Giel Berden Jos Oomens P B Armentrout

Structural characterization of gas-phase ions of cysteine (Cys) and cysteine methyl ester (CysOMe) complexed to zinc and cadmium is investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using a free electron laser in combination with density functional theory calculations. IRMPD spectra are measured for [Zn(Cys-H)](+), [Cd(Cys-H)](+), [Zn(CysOMe-H)](+), [Cd(CysOMe-H)...

2006
J. SRINIVASA NARAHARI SASTRY

Ab initio quantum chemical calculations, G3B3, second-order Møller– Plesset (MP2), and the hybrid density functional method B3LYP were employed to compute the proton affinities of 24 heterocyclic amines. A range of basis sets are employed, starting from doublepolarization quality to triplequality basis set with augmented diffuse and polarization function. Experimental values were used to calibr...

Journal: :Journal of the American Chemical Society 2003
Daniel A Singleton Chao Hang Michael J Szymanski Matthew P Meyer Andrew G Leach Keith T Kuwata Jenny S Chen Alexander Greer Christopher S Foote K N Houk

The mechanism of the ene reaction of singlet ((1)delta(g)) oxygen with simple alkenes is investigated by a combination of experimental isotope effects and several levels of theoretical calculations. For the reaction of 2,4-dimethyl-3-isopropyl-2-pentene, the olefinic carbons exhibit small and nearly equal (13)C isotope effects of 1.005-1.007, while the reacting methyl groups exhibit (13)C isoto...

2007
Sankar Prasad De Sankarlal Ash Sudipta Dalai Ajay Misra

Potential energy (PE) curves for the intramolecular proton transfer in the ground (GSIPT) and excited (ESIPT) states of 1-hydroxy-2naphthaldehyde (1H2NA) and 2-hydroxy-3-naphthaldehyde (2H3NA) were studied using DFT/B3LYP(6-31G) and TD-DFT/ B3LYP(6-31G) level of theory, respectively. Our calculations suggest the non-viability of ground state intramolecular proton transfer for both the compounds...

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