So, if we look at the bottom here and the actual plot of the wave function, we see it starts high, very positive, 0 and it goes down 0 and it eventually hits zero, and goes through zero 0 and then becomes negative 0 and then never quite hits zero again, although it approaches zero.

我们看,这下面这是波函数，我们看到它开始很高，是正的，然后降低直到,然后它穿过，变成负的,最后接近,但没达到，在这个。

麻省理工公开课 - 化学原理课程节选