使用者:Chenxin199261/edition3

均勻電子氣，表示某一微觀體系的勢能和相關參數（通常為原子坐標）之間的函數關係，是勢能函數的圖像。勢能面用一個或更多的坐標去表示，當用一個坐標去表示時，勢能面通常被稱為「勢能曲線」。

勢能面概念被用在物理以及化學領域, 尤其是它們的理論研究分支。 勢能面可以被用來從理論層面理解由原子組成的物質的性質, 例如：搜尋分子的最低能量構形或者計算化學反應速率。

勢能面類似於對地形的描述：對於一個有兩個自由度的體系（例如：一個鍵長、一個鍵角），體系的勢能可以類比為地形的高度，兩個自由度可以類比為描述某位置的坐標。通過這樣的描述，體系勢能隨坐標的變化可以很直觀地被表示出來。

水分子勢能面: 勢能最低點對應優化後的水分子結構， O-H 鍵長 0.0958nm， H-O-H尖角為 104.5°

A potential energy surface (PES) describes the energy of a system, especially a collection of atoms, in terms of certain parameters, normally the positions of the atoms. The surface might define the energy as a function of one or more coordinates; if there is only one coordinate, the surface is called a potential energy curve or energy profile. An example is the Morse/Long-range potential.

It is helpful to use the analogy of a landscape: for a system with two degrees of freedom (e.g. two bond lengths), the value of the energy (analogy: the height of the land) is a function of two bond lengths (analogy: the coordinates of the position on the ground).

The PES concept finds application in fields such as chemistry and physics, especially in the theoretical sub-branches of these subjects. It can be used to theoretically explore properties of structures composed of atoms, for example, finding the minimum energy shape of a molecule or computing the rates of a chemical reaction.