Preamble: Part 1¶
- Each structure (geometry) has an associated unique energy - PES \(= f(R)\)
- The changes between geometry are smooth, and so too is the PES
- Can be very highly dimensional
Dimensionality/Degrees of freedom¶
- Formally the system is \(3n\) dimensional (\(n=\)atoms)
- Chemically speaking, the dimensionality is about relative dimensions so we use the formula \(3n-6\) where \(n>2\) (nonlinear molecules), just as in IR spectroscopy
Any PES that we can visualise is just a ⅔/4 dimensional “slice” of the whole multidimensional PES. This is useful for showing specific features of the landscape.