Download grooved golf course . An idealized funnel landscape. As the chain forms increasing numbers of intrachain contacts, and lowers its internal free energy, its conformational freedom is also reduced. Download smooth funnel . A rugged energy landscape with kinetic traps, energy barriers, and some narrow throughway paths to native.
Folding can be multi-state.
Download bumpy bowl . Download moat . Champagne Glass Landscape, to illustrate how conformational entropy can cause free energy barriers to folding. The 'bottleneck' or rate limit to folding is the aimless wandering on the flat plateau as the chain tries to find its way downhill. Download champagne .