Hybrid functional method

Density functional calculations employing the B3LYP hybrid functional method combined with an adequate one-particle description [70b] gave an overall... 

For readers wishing to reach a better appreciation of papers regarding the formulation of interaction potentials, we add that there is another way of introducing electron correlation effects in the calculations. It is based on the density functional theory (DFT). There is a variety of DFT methods (detailed information can be found in the quoted monograph ) a family of these methods again makes use of MOs they are called hybrid functional methods and give, on average, better results than other correlated methods at a lower computational cost. 

Hybrid Hartree-Fock/Density Functional Methods... 

To overcome these limitations, the hybrid QM-MM potential can employ ad initio or density function methods in the quantum region. Both of these methods can ensure a higher quantitative accuracy, and the density function methods offer a computaitonally less expensive procedure for including electron correlation [5]. Several groups have reported the development of QM-MM programs that employ ab initio [8,10,13,16] or density functional methods [10,41-43]. 

Only the values computed by the hybrid functionals and MP2 are at all reasonable, and the B3PW91 value is in excellent agreement with experimental observations. Thi MP2 and B3LYP values are only modestly outside of the desired accuracy of 2 kcal-mol In Chapter 7, we will consider methods which were developed to consistently produce such very accurate thermochemical results. 

Quantum-chemical calculations which utilize the density functional theory (DFT) are now perhaps amongst the most frequently performed because of their relatively low cost and high accuracy. Structural results obtained from DFT based methods are often as good as those derived from MP2 calculations. It is well documented that DFT methods, especially those involving hybrid functionals such as B3LYP, B3P86 and B3PW91, yield reliable... 

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