نتایج جستجو برای: b3lyp

تعداد نتایج: 3756  

Journal: :The Journal of chemical physics 2015
Harley R McAlexander T Daniel Crawford

We report the first computations of circularly polarized luminescence (CPL) rotatory strengths at the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) level of theory. Using a test set of eight chiral ketones, we compare both dipole and rotatory strengths for absorption (electronic circular dichroism) and emission to the results from time-dependent density-functional theory (TD...

Journal: :Caucasian journal of science 2021

The potential energy curves (PEC) of 2 Chalcone (E)-3-(Furan-2-yl)-1-Phenylprop-2-en-1-one (1) were calculated as a function dihedral angle φ(C8-C9-C10-O1) at both ab initio Hartree–Fock (HF) and Density Functional Theory (DFT) using the B3LYP functional together with 6-311++G (d,p) basis set syn- anti-conformers corresponding low conformers determined. optimized molecular structures, vibration...

Journal: :Magnetic resonance in chemistry : MRC 2004
Ola B Lutnaes Torgeir A Ruden Trygve Helgaker

Density functional theory, in particular, with the Becke-3-parameter-Lee-Yang-Parr (B3LYP) hybrid functional, has been shown to be a promising method for the calculation of indirect nuclear spin-spin coupling constants. However, no systematic investigation has so far been undertaken to evaluate the capability of B3LYP to calculate these coupling constants accurately, taking properly into accoun...

Journal: :The Journal of chemical physics 2007
Denis Jacquemin Eric A Perpète Giovanni Scalmani Michael J Frisch Rika Kobayashi Carlo Adamo

Using the long-range correction (LC) density functional theory (DFT) scheme introduced by Iikura et al. [J. Chem. Phys. 115, 3540 (2001)] and the Coulomb-attenuating model (CAM-B3LYP) of Yanai et al. [Chem. Phys. Lett. 393, 51 (2004)], we have calculated a series of properties that are known to be poorly reproduced by standard functionals: Bond length alternation of pi-conjugated polymers, pola...

Journal: :Organic & biomolecular chemistry 2006
Seiichi P T Matsuda William K Wilson Quanbo Xiong

Most quantum mechanical studies of triterpene synthesis have been done on small models. We calculated mPW1PW91/6-311+G(2d,p)//B3LYP/6-31G* energies for many C30H51O+ intermediates to establish the first comprehensive energy profiles for the cationic cyclization of oxidosqualene to lanosterol, lupeol, and hopen-3beta-ol. Differences among these 3 profiles were attributed to ring strain, steric e...

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: :The Journal of chemical physics 2006
Martin J Paterson Ove Christiansen Filip Pawłowski Poul Jorgensen Christof Hättig Trygve Helgaker Paweł Sałek

We present a detailed study of the effects of electron correlation on two-photon absorption calculated by coupled cluster quadratic response theory. The hierarchy of coupled cluster models CCS, CC2, CCSD, and CC3 has been used to investigate the effects of electron correlation on the two-photon absorption cross sections of formaldehyde (CH2O), diacetylene (C4H2), and water (H2O). In particular,...

Journal: :The Journal of chemical physics 2007
Denis Jacquemin Eric A Perpète Miroslav Medved' Giovanni Scalmani Michael J Frisch Rika Kobayashi Carlo Adamo

Using the long-range corrected (LC) density functional theory (DFT) scheme introduced by Iikura et al. [J. Chem. Phys. 115, 3540 (2001)] and the Coulomb-attenuating model (CAM-B3LYP) of Yanai et al. [Chem. Phys. Lett. 393, 51 (2004)], we have calculated the longitudinal dipole moments and static electronic first hyperpolarizabilities of increasingly long polymehtineimine oligomers. For comparis...

Journal: :The Journal of organic chemistry 2000
A García-Granados E Melguizo A Parra Y Simeó B Viseras J A Dobado J Molina J M Arias

Different lipase enzymes have been tested in order to perform regioselective acetylations on the eudesmane tetrol from vulgarin. High yields (95%) of 1,12-diacetoxy derivative (4) were achieved in 1 h with Candida antarctica lipase (CAL). However, only the 12-acetyl derivative (6) was obtained in similar yield with Mucor miehei (MML) or Candida cylindracea (CCL) lipases. The enzymatic protectio...

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