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Molecular Orbitals

Molly Roesch

Molecular orbitals (MOs) are the molecular analogue to atomic orbitals. Atomic orbitals are where electrons can be “found”, and atomic orbital diagrams are used to indicate the energy, angular momentum, and spin of all electrons within an atom using symbols like…

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Møller-Plesset Perturbation Theory

Bhavnesh Jangid

Perturbation theory is used to approximate the true solution of the system by building on the solution resembling the actual solution. The mean-field method, like Hartree-Fock (HF), extracts most electronic energy but lacks correlation energy (corresponds to interactions between electrons). This correlation energy contributes slightly to the total energy but is necessary to give the qualitative correct electronic structure of the molecule. The Møller-Plesset perturbation theory of second-order (MP2) is the simplest many-body perturbation theory (MBPT) method to obtain the correlated wave-functions by adding corrections to the HF wave-function.

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