Question

Please help with this physical chemistry question, thank you!

2. What is the Born-Oppenheimer Approximation and why is it useful? Refer to the Hamiltonians for H2 and H2 in your explanation. 3. What is an LCAO? What is the difference between LCAO's used to describe molecular orbitals and those used to describe hybrid orbitals? Draw sketches as part of your explanation.

Answer 1

1. The Born-Oppenheimer Approximation is the assumption that the motion of atomic nuclei and electrons in a molecule can be separated, in quantum chemistry and molecular physics. The BO Approximation is named after Max Born and J. Robert Oppenheimer. It is used in quantum chemical calculations of molecular wave functions, especially for large molecules. It simplifies the computation of energy and wavefunction of an average-sized molecule. The total wavefunction of the molecule is broken down into electronic and nuclear components.