TZ2P calculation

SDCI/TZ2P calculations of Ishii et al (47). (c) this work... 

We have considered the larger AI4-AI6 clusters using both ab initio calculations and the parameterized model (9). The results for AI4 and AI5, summarized in Table IV, show that the parameterized model and ab initio calculations agree well on the relative energetics if both the two- and three-body interactions are included. For Ale it is difficult to treat all the structures at the TZ2P-CPF level, but for the structures considered, there is reasonable agreement between the ab initio and model results. 

When the parameters deduced from the calculations on AI2 and AI3 are applied to bulk Al, the cohesive energy is too small and the bond length is too large. The small cohesive energy is expected because our computed AI2 at the TZ2P-CPF level is only 71% of the experimental value (42.46). The bulk values are in much better agreement with experiment if the model is parameterized using the experimental and r values for the E state. Hence, the... 

TZ2P basis set from Ref. (37). SF models employ the X ground reference. The SF-CIS, SF-CIS(D), and SF-OD results are from Refs, calculated at the FCI/TZ2P optimized geometries. 

For an explicit examination of the basis set superposition error on weakly bound cationic structures at various theoretical levels, we performed full counterpoise calculations as outlined in Section IIB (Table 5). Table 5 demonstrates nicely that the magnitude of the BSSE is indirectly proportional to the size of the basis set at TZ2P, the error is on the average only about a quarter of that at DZP. This effect becomes more apparent with increased incorporation of electron correlation. At our best theoretical level, the BSSE amounts to only 0.1 kcal mol" (Table 5), which is insignificant for the dissociation energy of about 1.5 kcal mol". ... 

It is interesting to see what kind of MCD spectrum will be predicted by the parameters of Table I. Five simulated spectra are plotted in Fig. 2. These spectra are derived from the B-term parameters from Direct calculations with the DZP, TZ2P, and QZ3P-1D basis sets and the SOS(250) Approx and Im[V] calculations with the QZ3P-3D basis set. The simulated spectra were obtained from the MCD parameters following Eq. (1) or (33)... 

FIGURE 13. Experimental and calculated [GIAO/(MP2/TZ2P(Si)TZP(C)DZ(H))] chemical shifts of 75c and 75d, respectively. 15N chemical shifts are relative to NH3. The reported experimental 15N chemical shift (relative to CH3N0298a) was corrected using the experimental difference of 380 ppm between the 15N chemical shifts of CH3NO2 and NH3. Reproduced by permission of VCH Verlagsgesellschaft from Reference 102... 

FIGURE 5. Calculated PES (relative energies kcal mol ) of FESiC at the CCSD(T)/TZ2p(fd)//CCSD (T)/ TZ2p+ZPE level of theory2978... 

Calculations have been carried out on the. S n2 reactions between chloride ion and methyl chloride or chlorosilane at several DFT levels of theory up to the OLYP/TZ2P level.102 The OLYP/TZ2P method gave much better (excellent compared with the CCDD(T)/aug-cc-pVQZ level) values than the other density functionals for both the geometry and the energies of the reactant complex and transition state for the methyl chloride reaction and the stable transition complex that forms in the chlorosilane reaction. 

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