The LCAO SCF Method
- This approach of writing the unknown molecular orbitals in terms of a
known as the linear combination of atomic orbitals (LCAO) approach.
- Classic qualitative approach to molecular orbital theory.
- Originally introduced with the idea of using atomic orbitals as the basis, but
this creates problems.
- To form F, we must be able to compute the integrals over the one-
and two-electron operators in the Hamiltonian.
Other choices of basis functions
GTO basis sets
- Cannot solve H exactly with finite expansion in GTOs (needs only one
- Combination of several GTOs much better - need bigger GTO basis sets than STO
- Some GTO sets combine a few GTOs together into one basis function before we
start (contracted basis functions).
- Perform quite well: virtually all electronic structure calculations use