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raman
- 8
- 0
Can some one please tell me the physical meaning of the correlation energy. It is not clear however i know that it comes from the hatree-product ( expanding basis set). Also why do we need to model exchange effects.
The Hatree-Fock formalism is a mathematical method used in quantum chemistry to approximate the electronic wavefunction of a system. It is based on the idea of treating each electron in a system as moving independently in an average field created by all the other electrons.
Correlation energy is the energy that arises due to the interactions between electrons in a system. In Hatree-Fock formalism, it is not explicitly accounted for, but is instead approximated through the use of mean-field theory.
Hatree-Fock formalism takes into account exchange effects by using the antisymmetric nature of the electronic wavefunction. This means that the wavefunction must change sign when the positions of two electrons are exchanged. This leads to the inclusion of the exchange integral, which accounts for the repulsion between electrons with the same spin.
Hatree-Fock formalism is limited in its ability to accurately describe systems with strong electron correlation, such as molecules with multiple unpaired electrons or molecules with highly delocalized electrons. It also does not account for relativistic effects.
In practice, Hatree-Fock formalism is often used as a starting point for more advanced methods that can account for electron correlation more accurately. It is also used to calculate molecular orbitals, which are then used in other calculations such as determining molecular properties or predicting chemical reactions.