- Obtain the spectrum of the LCAO model of several orbitals
## Looking back
## Looking back
So far we have:
So far we have:
...
@@ -133,6 +141,16 @@ An occupied $\psi_-$ increases the molecule energy as the atoms move closer ⇒
...
@@ -133,6 +141,16 @@ An occupied $\psi_-$ increases the molecule energy as the atoms move closer ⇒
Therefore if each atom has a single electron in the outermost shell, these atoms attract, if there are 0 or 2 electrons, the net electron force cancels (but electrostatic repulsion remains).
Therefore if each atom has a single electron in the outermost shell, these atoms attract, if there are 0 or 2 electrons, the net electron force cancels (but electrostatic repulsion remains).
*[LCAO]: Linear Combination of Atomic Orbitals
!!! summary "Learning goals"
After this lecture you will be able to:
- Explain the origins of interatomic forces
- Compute vibrational spectra of small molecules in 1D
- Write down Hamiltonians and equations of motion of bulk materials (but not yet solve them)
## Adding repulsion
## Adding repulsion
If bringing two atoms closer would keep increasing energy, any covalent bond would collapse; eventually the two atoms must start repelling (at least when the nuclei get close, but really already much earlier).
If bringing two atoms closer would keep increasing energy, any covalent bond would collapse; eventually the two atoms must start repelling (at least when the nuclei get close, but really already much earlier).