DFT B3LYP methods

In another DFT study, the reductive decomposition of artemisinin 9a was investigated by the DFT B3LYP method, together with the 6-31G(d) and 6-31- -G(d,p) basis sets <2006BMC1546>. 

Table 2 Anharmonic frequencies (in cm-1) for the target modes of the different model structures as obtained using Eq. (1) with the one mode potential generated by the DFT/B3LYP method with a 6-31++G(d,p) basis set and the two- and threemode PES obtained by the PM3 approach.

Table 6 Anharmonic frequencies (in cm-1) for the target modes of the AT-(H20)2 model calculated using the anharmonic expansion, Eq. (2) and the DFT/B3LYP method with a 6-31++G(d,p) basis set. The 4D model is compared with a 6D model which includes in addition the most strongly coupled water stretching and bending modes at the N6-H site whose anharmonic frequencies are 3752 cm-1 and 1588 cm-1, respectively. Also given are results for a 4D model which does not include water molecules [59]. The experimental assignment is shown as well ( /nh2 from Ref. [59], the other modes from Refe. [7-9,14,34-38]).

Lindgren et al. studied the excited state and phosphorescence of platinum(II) acetylides (5.9) with the DFT/B3LYP method [103], The calculated UV/Vis absorption spectra revealed that the orientation of the phenyl rings relative to the P-Pt-P axis has a strong correlation with the intensity of the absorption band. The broken symmetry phenomenon was also confirmed in the lowest triplet excited state, which leads to a OC-Ph bond on one side and a C=C=C bond on the opposing side. Quadratic response calculations of spin-orbit coupling showed that the intensity of the phosphorescence of these complexes arises mainly from the a—>n type T- l) transitions localized at the OC-Pt-P fragment, but not from the delocalized 7t—type transitions. The quadratic response calculations also reproduced an increase of xR from PEj to PE2 (5.9), which was also determined experimentally. 

CPH(327)269>, calculated by OVGF method and the 6-311 -I-I-G basis set. " <2006CPH(327)269>, calculated by HF method and the aug-cc-pVTZ basis set. <2006CPH(327)269>, calculated by DFT/B3LYP method and the aug-cc-pVTZ basis set. 

Quantum mechanical calculations using ab initio method (Moller-Plesset perturbation theory MP2) and DFT-B3LYP method... 

Lewis et al. [71] calculated four possible decomposition pathways of the a-HMX polymorph N-NO2 bond dissociation, HONO elimination, C-N bond scission, and the concerted ring fission. Based on the energetics, it was determined that N-NO2 dissociation was the initial mechanism of decomposition in the gas phase, while they proposed HONO elimination and C-N bond scission to be favorable in the condensed phase. The more recent study of Chakraborty et al. [72], using the DFT(B3LYP) method, reported detailed decomposition pathways of the P-HMX, the stable polymorph at room temperature. It was concluded that consecutive HONO elimination (4HONO) and subsequent decomposition into HCN, OH and NO are energetically the most favorable pathways in the gas phase. The results also showed that the formation of CH2O and N2O could occur preferably from secondary decomposition of... 

A comparison of various computational methods is made in the C-H o-bond activation of methane by palladium(II) formate complex, Pd(t -02CH)2 [9]. As shown in Table 8, the DFT(B3LYP) method provides considerably smaller activation barrier and exothermicity than the other methods such as MP2 to MP4(SDQ) and CCSD(T) methods. Although the activation barrier and the exothermicity moderately fluctuate around MP2 and MP3 levels, they converge to about 20 and 6-7 kcal/mol, respectively, upon going to CCSD(T) from MP3. 

The similar results were presented for the C-H o-bond activation of benzene by Pd(tT -02CH)2. These results suggest that the MP4(SDQ) and CCSD(T) methods with proper basis sets provide reliable results in this reaction but we had better apply carefully the DFT(B3LYP) method to this kind of reaction. Because this reaction takes place in a heterolytic C-H o-bond scission, as will be described below, it is considered likely that the weak point of the DFT(B3LYP) method here results from the polarized electron distribution of this reaction system. 

The similar Ir-catalyzed direct borylation of benzene with diboron was recently reported experimentally [52] and its full catalytic cycle was theoretically investigated with the DFT(B3LYP) method [53]. In this reaction, the iridium(III) complex, Ir(bpy)(Beg)3 (bpy=2,2 -bipyridine eg=ethyleneglycolate),is an active... 

Jang et al. [12] calculated the pK values of uracil and some of its five-substituted derivatives, using the DFT/B3LYP method in combination with the PB continuum solvation model (Fig. 7.5). 

Fig. 7.1 Snapshots of the dynamics of the sequential ionization model of Ceo- The DFT/B3LYP method with the 3-21G basis set is used. The applied pulse is a Gaussian pulse of Tpg = 30 fs, fpeak = 7.0 X 10 W/cm, and X = 1,800 nm. The polarization direction is the vertical direction. Time = 0 fs is the time of the peak of the laser pulse. The temporal profile of the applied electric field is sketched in the upper left comer of each snapshot of Ceo the open circle in the field profile designates the field strength at the time. In this model, Qo is sequentially ionized from charge = 0 to denoted by charge = 12 under laser irradiation. Qo is elongated along the...

Table 1. Activation barriers Ea, energies of reaction Ej (in kcal/mol), and their errors AE with respect to the pure DFT(B3LYP) method for the oxidative addition of H2 to Pt(P(/-Bu)3)2 calculated with various ONIOM...

---