Density functional theory hybrid

Orlova et al. (2003) theoretically studied the mechanism of the firefly bioluminescence reaction on the basis of the hybrid density functional theory. According to their conclusion, changes in the color of light emission by rotating the two rings on the 2-2 axis is unlikely, whereas the participation of the enol-forms of oxyluciferin in bioluminescence is plausible but not essential to explain the multicolor emission. They predicted that the color of the bioluminescence depends on the polarization of the oxyluciferin molecule (at its OH and O-termini) in the microenvironment of the luciferase active site the... 

Amara, P., Volbeda, A., Fontecilla-Camps, J. C., Field, M. J., 1999, A Hybrid Density Functional Theory/Mo-lecular Mechanics Study of Nickel-Iron Hydrogenase Investigation of the Active Site Redox States , J. Am. Chem. Soc., 121, 4468. 

Blomberg, M. R. A., Siegbahn, P. E. M., Svensson, M., 1996, Comparisons of Results From Parameterized Configuration Interaction (PCI-80) and From Hybrid Density Functional Theory With Experiments for First Row Transition Metal Compounds , J. Chem. Phys., 104, 9546. 

However, one feature of the HF potential is that it is not a local potential. In the case of perfect data (i.e. zero experimental error), the fitted orbitals obtained are no longer Kohn-Sham orbitals, as they would have been if a local potential (for example, the local exchange approximation [27]) had been used. Since the fitted orbitals can be described as orbitals which minimise the HF energy and are constrained produce the real density , they are obviously quite closely related to the Kohn-Sham orbitals, which are orbitals which minimise the kinetic energy and produce the real density . In fact, Levy [16] has already considered these kind of orbitals within the context of hybrid density functional theories. 

Potassium cation affinities of several azoles and other compounds in the gas phase were calculated by hybrid density functional theory [B3-LYP with 6-311 + G(3df, 2p) basis set] <2003CEJ3383>. There is a striking difference in binding energies of 177- and 277-1,2,3-triazoles. Some of the collected data are as follows ... 

The quantum-mechanical energy curve was calculated at the B3LYP/6-311++G level of hybrid density-functional theory, as described in Appendix A. However, due to B3LYP convergence failures beyond Ji 3A, the quantities shown in Figs. 2.4—2.8 were calculated at HF/6-311++G" level. 

Because of the presence of two azide groups in positions adjacent to the ring nitrogen atoms in compound 13a, valence bond isomerization can result in formation of 6-azido-7-methyltetrazolo[l,5-A pyridazine 14a, 6-azido-8-methyltetrazolo[l,5-A pyridazine 15a, and the bis-tetrazole compound 16a. Calculations have been carried out by using hybrid density functional theory (B3LYP/6-311+G(d,p)) and complete basis set treatments (CBS-4M). All calculations revealed that the 8-methyl derivative 15a is the most stable isomer. Similar studies on the triazide derivative 13b, however, indicated that in this case the equilibrium is shifted to the 7-methyl form 14b. All these conclusions proved to be in entire agreement with the experimental findings (see Section 11.18.3.2.). 

The majority of the molecular-scale information concerning the effects of structure and local chemistry on proton dissociation and separation in PEM fragments alluded to previously " were initially determined using HE theory and split valence local basis sets. Refinements to the equilibrium configurations were made using both Mailer-Plesset (MP) perturbation schemes and hybrid density functional theory (described below). 

MNDO or ab initio calculations (Table 5.3). Further confirmation for the preference of 1,2-addition was established by ab initio calculation of the C-H bond energy in hydrogenated fullerenes [35]. Hybrid density functional theory using the B3LYP functional with the 6-31 G(d,p) basis set leads to the bond energies shown in Table 5.3. The most stable bond is found in 1,2 adducts with a bond energy of 2.86 eV, followed by a bond energy of 2.69 eV in 1,4-adducts. All the other addition patterns such as 1,3 addition or addition to a [5,6] bond lead to less stable C-H bonds (Table 5.3). 

The 1,2-hydrogen shift isomers of neutral (singlet and triplet) thiazole and its radical cation have been investigated87 by a combination of mass spectrometric experiments and hybrid density functional theory calculations. An unexpected isomerization of A-aryl-3-amino-4-nitroisothiazole-5(2//)-imines (71) to 2-(benzothiazol-2-yl)-2-nitro-ethene-1,1-diamines (72) has been reported.88... 

Hybrid density functional theory ab initio calculation method Cluster (molecular connectivity)... 

Winget, P., Thompson, J.D., Xidos, J.D., Cramer, C J., and Truhlar, D.G., Charge model 3 a class IV charge model based on hybrid density functional theory with variable exchange, J. Phys. Chem. A, 106, 10707-10717, 2002. 

Amara P, Volbeda A, Fontecilla-Camps JC, Field MJ (1999) A hybrid density functional theory/molecular mechanics study of nickel-iron hydrogenase investigation of the active site redox states J. Am. Chem. Soc. 121 4468—1477... 

Goerigk L, Grimme S (2009) Calculation of electronic circular dichroism spectra with time-dependent double-hybrid density functional theory. J Phys Chem A 113 767-776... 

In a third theoretical model the [FeNi]-hydrogenase from D. gigas is modeled using a hybrid density functional theory-molecular mechanics (DFT/MM) method [92]. In this model approximately 30 atoms of the active site (including the four cysteine residues) are modeled with DFT while molecular mechanics is used for the rest of the atoms within a A radius (about 300 atoms). The next shell includes about 10 000 protein and solvent atoms within 27 A of the active site whose posi-... 

Kudin, K., Scuseria, G., Martin, R. (2002). Hybrid density-functional theory and the insulating gap of UOj. Phys. Rev. Lett. 89,266402. 

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