Note that, as discussed later, an important difference between the Born-Oppenheimer and Born-Huang adiabatic approximations is that, in the inverted region, the Born-Huang adiabatic approximation typically still generates transition states rather than points of inflection.
12.
Because this procedure of recomputing the electronic wave functions as a function of an infinitesimally changing nuclear geometry is reminiscent of the conditions for the adiabatic theorem, this manner of obtaining a PES is often referred to as the " adiabatic approximation " and the PES itself is called an " adiabatic surface ".
