Density functional theory, methane

We win run this job on methane at the Hartree-Fock level using the 6-31G(d) basis our molecule specification is the result of a geometry optimization using the B3LYP Density Functional Theory method with the same basis set. This combination is cited... 

Bernardi, F., Bottom, 1997, Polar Effect in Hydrogen Abstraction Reactions from Halo-Substituted Methanes by Methyl Radical A Comparison Between Hartree-Fock, Perturbation, and Density Functional Theories , J. Phys. Chem., 101, 1912. 

Although dimethylberyllium is a coordination polymer in the solid state,27 it has long been known to be monomeric in the gas phase.28 It has also been found to be monomeric when synthesized from the co-condensation of laser-ablated beryllium atoms and a methane/argon mixture at 10 K.11 Formed in conjunction with several other species, including hydrides (see Section 2.02.2.4), (CH3)2Be was identified from its infrared absorption bands, which were compared to DFT-calculated frequencies (DFT = density functional theory). 

A systematic study to identify solid oxide catalysts for the oxidation of methane to methanol resulted in the development of a Ga203—M0O3 mixed metal oxide catalyst showing an increased methanol yield compared with the homogeneous gas-phase reaction.1080,1081 Fe-ZSM-5 after proper activation (pretreatment under vacuum at 800-900°C and activation with N20 at 250°C) shows high activity in the formation of methanol at 20°C.1082 Density functional theory studies were conducted for the reaction pathway of the methane to methanol conversion by first-row transition-metal monoxide cations (MO+).1083 These are key to the mechanistic aspects in methane hydroxylation, and CuO+ was found to be a likely excellent mediator for the reaction. A mixture of vanadate ions and pyrazine-2-carboxylic acid efficiently catalyzes the oxidation of methane with 02 and H202 to give methyl hydroperoxide and, as consecutive products, methanol and formaldehyde.1084 1085... 

Bernardi F, Bottoni A. Polar effect in hydrogen abstraction reactions from halo-substituted methanes by methyl radical a comparison between Hartree-Fock, perturbation, and density functional theories. J Phys Chem A 1997 101(10) 1912—1919. 

FIGURE 17. Postulated mechanism for Q reaction with methane based on Density Functional Theory calculations. (Siegbahn and Crabtree, 1997). 

Acac = acetyacetonate BArf = tetra(3,5-bis(trifluorome-thyl)phenyl)borate anion bridge = 1,3-diisocyanopropane COD = cycloocta-1,5-diene COE = cyclooctene DFT = Density Functional Theory dimen = 2,1,8-diisocyanoment-hane DMAD = dimethylacetylene dicarboxylate DMSO = dimethylsulfoxide dpmp = bis(diphenylphosphinomethyl) phenylphosphine DPPB = l,4-bis(diphenylphosphino)but-ane DPPE = l,2-bis(diphenylphosphino)ethane DPPM = bis(diphenylphosphino)methane en= 1,2-diaminoethane hfac = hexafluoroacetylacetonate HFB = hexafluorobut-2-yne HOTf = trifluoromethanesulfonic acid (triflic acid) MLCT = Metal Ligand Charge Transfer MO/MM = Molecular Orbital/Molecular Mechanics NBD = bicyclo[2. 2.1]heptadiene OTf = trifluoromethanesulfonate (triflate) ion OTs = p-toluenesulfonate (tosylate) ion /j-anis = /7-MeOC6H4 pip = piperidine pn = 1,2-diaminopropane PPN+ = bis(triphenylphosphine)iminium cation p-to = p-MeCeUt pz = pyrazolate QM/MM = Quantum Mechan-ics/Molecular Mechanics TFB = tetrafluorobenzobarrelene TM4 = 2,5-diisocyano-2,5-dimethyIhexane tn = 1,3-diami-nopropane. 

MePTZ = lO-methylphenothiazine 2,3-dpp = 2,3-bis (2-pyridyl)pyrazine 2,9-Me2-4,7-Ph2-phen = 2,9-dimethyl-4,7-diphenyl-l,10-phenanthrolme 2,9-Me2-phen = 2,9-dimethyl-1,10-phenanthroline 3,4,7,8-Me4-phen = 3,4,7,8-tet-ramethy 1-1,10-phenanthroline 4,4 - NH2 2-bpy = 4,4 -dia-mino-2,2 -bipyridine 4,4 -Me2-bpy = 4,4 -dimethyl-2,2 -bipyridine 4, 4 -Ph2-bpy = 4,4 -diphenyl-2,2 -bipyridine 4, 4 - Bu2-bpy = 4,4 -di-tert-butyl-2,2 -bipyridine 4,7-Me2-phen = 4,7-dimethyl-l,10-phenanthroline 4-MeOPh-HPh bpy = 4 -(4-methoxyphenyl)-6 -phenyl-2,2 -bipyridine 4-Me-phen = 4-methyl-1,10-phenanthroline 5,6-Me2-phen = 5,6-dimethyl-l,10-phenanthroline 5-Ph-phen = 5-phenyl-1,10-phenanthroline bimy = benzimidazol-2-ylidene biq = 2,2 -biquinoline bpy = 2,2 -bipyridine bpy-dvb-bpy = 1,4-bis[2-(4 -methyl-2,2 -bipyrid-4-yl)ethenyl]benzene bpy-pyrl = 4-(2-pyrrol-l-ylethyl)-4 -methyl-2,2 -bipyridine bpy-pyr2 = 4,4 -bis((3-pyrrol-l-ylpropyloxy)carbonyl)-2,2 -bipyridine BSA = bovine serum albumin BTA = bis(trimethylsilyl)acetylene chrysi = 5,6-chrysenequinone diimine COD = 1,5-cyclooctadiene DAB = 1,4-diaza-1,3-butadiene DFT = density functional theory dmb =1,8-diisocyano-/ -menthane dmb-tol = 4-methyl-4 -(iV-methyl-/ -tolylaminomethyl)-2,2 -bipyridine dmpe = l,2-bis(di-methylphosphino)ethane dmpm = bis(dimethylphosphino) methane dpmp = bis(diphenylphosphinomethyl)phenylphos-phine dppb = l,2-bis(diphenylphosphino)benzene dppe = l,2-bis(diphenylphosphino)ethane dpp-HCNN = 2,9-di-... 

A new approach based on a combination of the non-local density functional theory and the Bender equation of state was successfully applied to high-pressure (up to SO MPa) argon, nitrogen, methane and helium adsorption. The approach allows reliably determining pore size distribution and adsorbent density, and most importantly it does not require helium experiments to determine the skeletal density. 

Fig. 3 Calculated energies of solvation v. experimental values for (from left to right) water, ethanol, methanol, and methane in water. The diagonal line gives perfect agreement, the open circles results with the joint density-functional theory for electronic structure of solvated systems, and the other symbols results from different continuum approaches. Reproduced with permission from ref. 54. 

Basis set superposition error in MP2 and density-functional theory A case of methane-nitric oxide association ... 

Shaik and co-workers have carried out a number studies using density functional theory based quantum chemical and QM/MM techniques to examine various aspects of the mechanism of alkane hydroxylation by cytochrome P450.178 181 These studies included, for example, calculation of the potential energy surface for the so-called rebound mechanism with methane as a substrate for two spin states, the high spin (HS) quartet state and low spin (LS) doublet state. In the rebound mechanism, Compound I initially abstracts a... 

Density functional theory and MP2 calculations of the transition states and reaction paths on coupling reaction of methane through plasma108... 

Figure 2.6. Potential energy diagram for the steam methane reforming over Ni(lll) and Ni(211) surfaces based on the density functional theory (DFT) study. Adapted from Rostrup-Nielsen et al.10...

DCTL. See coal, -to-hquids, direct DEA. See acid gas removal, dietheanolamine deactivation catalyst, 106-109 decomposition methane, 138, 146 pyrolytic, 6 dehydrocyclization, 58 dehydrogenation, 58 density functional theory (DFT), 30 deposition... 

Tanaka, H., El-Merraoui, M., Steele, W.A., and Kaneko, K. (2002). Methane adsorption on single-walled carbon nanotube a density functional theory model. Chem. Phys. Lett., 352, 3—41. 

The reaction of Ta" with methane in the gas phase has been computationally investigated using approximate density functional theory [51], The overall reaction sequence... 

Puddephatt etal. [41] have studied the C-H or C-C bond activation in the alkane complexes [PtMe(CH4)L2] or [PtMe(CHjCH3)L2] (L = NH3 or PH3) as well as the reductive elimination of methane or ethane from the five-coordinate model complexes [PtHMe2L2] or [PtMesLi], respectively, by carrying out extended Hiickel molecular orbital calculations and density functional theory. The oxidative addition and reductive elimination reactions occur by a concerted mechanism, probably with a pinched trigonal-bipyramidal complex on the... 

The lack of a dispersion term in modem density functional theory leads to a repulsive interaction between hydrocarbons.B3LYP, 6-31g MP2, and cc-pVQZ 33 MP2 methane dimer potential curves are collected in Figure 12. The cc-pVl Z B3LYP curve is purely repulsive due to the lack of dispersion. The... 

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