Properties of the stationary points (geometries, energies, and vibrational frequencies, etc.) and those along the minimum energy paths (MEPs) are important and necessarily only required to predict the reaction selectivity, competition, and reactivity within the framework of the transition state theory (TST), or Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Despite powerful, efficient, and successful in many cases, these statistical theories may fail and nonstatistical dynamic effects have to be taken into account. For instance, the minimum along the reaction coordinate may be not passed by in a reactive trajectory if a flat potential energy region, following a rate-limiting transition state, leads to multiple products. Dynamic effect may also occur if the potential energy surface (PES) involves the so-called "bifurcating energy surface": the rate-limiting transition state was followed by another transition state that interconverts products, and the reactants can lead to different products through the same rate-limiting transition state. Besides, products can be reached via the so-called roaming mechanism without through any conventional tight transition state. Such a roaming mechanism is again largely determined by the potential energy topology. Further, it has been well recognized that different forms of energy (translations, vibrations, and rotations) may possess disparate influences on the detailed scattering dynamics. Indeed, the potential energy surface (PES) is a key factor that is related to molecular equilibrium structures, interactions, various spectra, energy transfer, reaction kinetics, and dynamics. Different research targets may have distinct requirements for the PES.