Functional B3LYP

Sclufi n Here are the results we obtained with the SVWN5, BLYP and B3LYP functionals, along with Tozer and Sosa s HP and MP2 results. All frequencies are scaled, and wt have limited our consideration to the frequencies of interest ... 

As was pointed out earlier (76AHCS1, p. 217), tautomeric equilibria for substituted isoindole-isoindolenine systems depend critically upon the substituents. Isoindole exists in the o-quinoid form 6. Computational results for the parent systems are given in Table III (99UP1). The results indicate that within the B3LYP functional only large basis sets provide reliable energy differences. 

Fig. 5.16 Calculated structure of ferrous nitrosyl tetraphenylporphyrin Fe(TPP)(NO), resulting from geometric optimization with the B3LYP functional and 6-3IG -I- VTZ basis set [101]. Color scheme cyan = iron, green = carbon, blue = nitrogen, red = oxygen (taken from [101])...

Voigt function to the 540 cm peak. It is very close to the expected value = 0.34 for a two-body Fe-NO oscillator. The calculated value = 0.39 (B3LYP functional) is in agreement with the experimental one. 

For the B3LYP functional an unsigned error with respect to the G2 data base of only slightly above 2 kcal/mol was determined. 

The best results are obtained with the hybrid schemes, the standard B3LYP functional and the new, one-parameter PBE1PBE protocol. Of course, one must keep in mind that independent of the particular functional chosen, large and flexible basis sets must be used. 

Hirata and Iwata, 1998, extended these studies to linear oligomers and an infinite linear hydrogen fluoride polymer. Also this study substantiates the applicability of the BLYP and B3LYP functionals, for which reasonable agreement with experiment has been found with respect to structure, binding energies and vibrational frequencies of the species explored. 

Table 13-3. Basis set dependence of activation (AEa) and reaction energies (AEr) computed using the B3LYP functional for the concerted gas-phase cycloaddition of ethylene to trans-butadiene [kcal/mol]. All calculations include zero-point vibrational contributions evaluated at the B3LYP/6-311+G(d,p) level.

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