Development of Modern Density Functional Methods: .. (CFMLHA)
Development of Modern Density Functional Methods: Combining the Correlation Factor Model and the Local
Start date: Apr 1, 2012,
End date: Mar 31, 2015
"The objective of the proposed project is the design of new approximation to the exchange-correlation energy of Kohn-Sham density functional theory (DFT). The work will be based on two different approaches to the exchange-correlation energy density. The so-called local hybrid approach relies on a position-dependent mixing of approximate DFT exchange and exactexchange. Alternatively, the exchange-energy density can be obtained from an exchange-correlation hole constructed by multiplying an exchange hole with a correlation factor. This is referred to as the correlation factor (CF) model. The two approaches appear to be quite different at first sight, however, both aim to recover exact exchange in regions of the system withnegligible correlation and they use the same local variables to achieve this goal. Building on the similarities, we will combine the strengths of these approaches while avoiding their problems. First, we propose to develop a new correlation factor model employing the exact exchange-energy density. Second, we suggest to develop a hybrid scheme with the local mixing coefficient derived based on the results of the correlation factor model. The CF ansatz, which does not itself involve any unknown parameters, will in this way help to replace the empirical parameters in a local hybridfunctional. Finally, we intend to compare the exchange-correlation holes of the correlation factor model with those of the local hybrids, which will serve for the mutual improvement of the holes."
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