https://doi.org/10.1351/goldbook.D01823
A surface, usually taken to be a hyperplane, constructed at right angles to the
minimum-energy path
on a potential-energy (reaction) surface
. In conventional transition-state theory
it passes through the highest point on the minimum-energy path. In generalized versions of transition-state theory the dividing surface can be at other positions; in variational transition-state theory
the position of the dividing surface is varied so as to get a better estimate of the rate constant
.