The electronic structure of polyatomic molecules can be described
approximately with LCAOMOs that involve only two atomic orbitals if
appropriate hybrid orbitals are used.
Qualitative descriptions of the electronic states of molecules can be
obtained by using general criteria for forming good bonding LCAOMOs.
Group theory can be used to obtain useful information about molecular
orbitals of polyatomic molecules.
Various semiempirical and ab initio techniques exist for carrying out
molecular quantum mechanical calculations, and software packages are
available to carry out these techniques.
