BLYP functionals

Pure DFT methods are defined by pairing an exchange functional with a correlation functional. For example, the well-known BLYP functional pairs Becke s gradient-corrected exchange functional with the gradient-corrected correlation functional of Lee, Yang and Parr. 

Here is a KS-LCAO calculation on water at the experimental geometry of 95.7pm and 104.5°. I chose the BLYP functional this comprises Becke s 1988... 

In the following, all isotropic hyperfine coupling constants were calculated using the BLYP functional and the EPR-II basis set. A full geometry optimization was done in all cases. 

Remarkably, the BLYP functional approaches or sometimes surpasses the accuracy of hybrid functionals if small basis sets are used (see Table 9-5). 

Here, the summation is over all atom pairs, CV 7 is the dispersion coefficient for the pair of atoms i and j (calculated from the atomic CV, coefficients), s< is a scaling factor which is chosen to be 1.4 in line with the value used for the BLYP functional [118], and Rij is the inter-atomic distance between atoms i and j. A damping function is used in order to avoid near singularities for small distances, given by ... 

During recent years DFT methods have been used to reproduce vibrational frequencies and IR intensities (dipole moment derivatives) with high accuracy (scaling factors are close to unity).29,60,61 We therefore used the B3LYP and BLYP functionals to calculate the spectra of la and its isotopomers, and indeed the calculated frequencies, isotopic shifts, and intensities are now in excellent agreement with the experimental values (Fig. 3).62 A careful reexamination... 

Three density functional theories (DFT), namely LDA, BLYP, and B3LYP, are included in this section. The simplest is the local spin density functional LDA (in the SVWN implementation), which uses the Slater exchange functional [59] and the Vosko, Wilk and Nusair [60] correlation functional. The BLYP functional uses the Becke 1988 exchange... 

The ordering of the reliability of the methods is similar to the results for the G2/97 test set seen previously. As expected from its known tendency for substantial overbinding, the local density method (LDA) performs poorest with a mean absolute deviation of 134 kcal/mol. The BLYP functional has a mean absolute deviation of 9.3 kcal/mol, while the B3LYP functional performs the best with a mean absolute deviation of 4.8 kcal/mol. In our previous study on the G2/97 test set that included seven functionals, the B3LYP function also had the lowest mean absolute deviation. 

Density functional theory (DFT) [9] is becoming increasingly important in determining chemical properties. Typical methods involve the BLYP functional and the hybrid B3LYP procedure. DFT methods are attractive in that they are often highly cost effective and therefore offer the possibility of application to quite large systems, provided that they are suitably reliable. 

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