Perdew-Wang 91

PW91 (Perdew, Wang 1991) a gradient corrected DFT method QCI (quadratic conhguration interaction) a correlated ah initio method QMC (quantum Monte Carlo) an explicitly correlated ah initio method QM/MM a technique in which orbital-based calculations and molecular mechanics calculations are combined into one calculation QSAR (quantitative structure-activity relationship) a technique for computing chemical properties, particularly as applied to biological activity QSPR (quantitative structure-property relationship) a technique for computing chemical properties... 

Different functionals can be constructed in the same way by varying the component functionals—for example, by substituting the Perdew-Wang 1991 gradient-corrected correlation functional for LYP—and by adjusting the values of the three parameters. 

Here rr runs over a and (i spins, and have been defined in eqs. (6.23) and (6.25), a and are fitting parameters, and Perdew-Wang parameterization of the... 

Table4.4 Spectroscopic properties for Au2 q= -1,0, + 1) using ab-initio (Hartree Fock, HF, second-order Moller-Plesset, MP2, and coupled cluster, CCSD(T)) and DFT (local spin-density approximation, LSDA, Perdew-Wang CCA, PW91, and Becke three-parameter Lee-Yang-Parr functional, B3LYP) methods at the RPPA level of theory.

TABLE 9.2 Perdew-Wang (PW91) Binding Energies of O and O2 on the Pt and Pt3Co Alloy Surfaces. Reprinted with Permission from Xu et al. [2004]... 

Becke, A. D., 1992b, Density Functional Thermochemistry. II. The Effect of the Perdew-Wang Generalized-Gradient Correlation Correction , J. Chem. Phys., 97, 9173. 

The equilibrium interconversion between an ethylene phosphite and a bicyclic spirophosphorane is shown to proceed by the insertion of the phosphite into the labile O-H bond of the hydroxyethyl ester. The mechanism is similar to the insertion of carbenes or nitrenes. Energy relationships of reaction intermediates were studied by MO RHF, MP2(full), MP4SDTQ, and DFT calculations. In most cases, they predicted that hydroxyethyl ethylene phosphates were more stable than the strained spirophosphoranes, which is not supported by the experimental evidence. The best correspondence to experimental data was obtained by DFT calculations with Perdew-Wang correlation functions <2003JST35>. 

B3LYP predicts a negative overall barrier if X = Y = Cl (i.e. a barrier between the entry and exit ion-molecule complexes that lies below the entrance channel). Adamo and Barone [79] demonstrated that their new mPWlPW91 (modified Perdew-Wang) functional at least yields the correct sign for this problem. 

In Ref. [12], Perdew and Burke made a graphical comparison of various GGA s. The popular functionals for exchange (Perdew-Wang 86 [8], Becke 88... 

Unless otherwise stated, all of our calculations used the generalized gradient approximation as defined by the Perdew-Wang 91 functional. In shorthand, we used PW91-GGA calculations. Unless otherwise stated k points were placed in reciprocal space using the Monkhorst-Pack method. Some specific details for the calculations from each section of the chapter are listed below. 

Nonempirical GGA functionals satisfy the uniform density limit. In addition, they satisfy several known, exact properties of the exchange-correlation hole. Two widely used nonempirical functionals that satisfy these properties are the Perdew-Wang 91 (PW91) functional and the Perdew-Burke-Ernzerhof (PBE) functional. Because GGA functionals include more physical ingredients than the LDA functional, it is often assumed that nonempirical GGA functionals should be more accurate than the LDA. This is quite often true, but there are exceptions. One example is in the calculation of the surface energy of transition metals and oxides. 

Reference TMS <513C(calc) = 183.5 ppm, geometry (Cl) B3LYP/6-31G(d) NMR calculation SOS DFT PW91 (Perdew-Wang 91) IGLO IB. 

Nonlocal DFT with the Perdew-Wang-91 exchange-correlation functional (Refs. 19 and 132). 

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