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I think I've understand why the real Eigenfunctions of Hamiltonian belong to a given irreducible representation and I've read that also MOs have to transform as irreducible representation due to the commutation properties of the individual hamiltonian and the point group operators.

My question is how the fact that real solutions have this symmetry is exploited in practice (no need complex discussions, only intuitive ones). And mainly if and how the fact that we try to construct correct symmetry MOs is exploited in methods like CI.

User Joan Triay
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Final answer:

In quantum chemistry, eigenfunctions with the correct symmetry properties simplify the computational task and allow for systematic prediction of electronic transitions. Exploiting these symmetries is crucial in methods like Configuration Interaction, which help us understand molecular properties and behaviors such as paramagnetism or electrical conductivity.

Step-by-step explanation:

The eigenfunctions of a Hamiltonian, which describe the quantum states of a system, must transform according to the symmetries represented by the various irreducible representations of the molecule's point group. This symmetry constraint arises due to the commutation of the Hamiltonian with the symmetry operations of the point group. In practical terms, exploiting the symmetry of molecular orbitals (MOs) is advantageous in computational chemistry methods such as Configuration Interaction (CI).

In CI and other quantum chemistry methods, we construct symmetry-adapted linear combinations of atomic orbitals (SALCs) to form MOs that comply with the symmetry properties of the molecule. This approach not only simplifies the complex task of solving Schrödinger's equation for many-electron systems but also allows for the systematic prediction and interpretation of electronic transitions, such as those between the HOMO and LUMO in molecular systems.

The Born interpretation and the Copenhagen interpretation are foundational concepts in quantum mechanics. These interpretations inform us about the nature of the wave function and how its square relates to probability densities, while symmetry considerations streamline computational efforts and enhance our understanding of molecular properties.

User Tiendv
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