Use of electron mass instead of the reduced mass to calculate the ground-state energy of the hydrogen atom gives-13606ev which is in error by7parts in13000.

用电子质量代替折合质量去计算氢原子基态能量给出- 13606电子伏，误差是13000分之7。

youdao

He goes back and redoes the calculation, only in this case he says what I am going to do is I am going to redo the calculation for helium, but I am going to consider not just the mass of the electron but the reduced mass of the system.

他回去重新做了计算，仅在这种情况下他才会说说我将要,为氦重做计算，但我认为,不只是电子的质量,还有系统质量的减少量。

麻省理工公开课 - 固态化学导论课程节选