- #1
Zacarias Nason
- 68
- 4
As it says; I was looking over some provided solutions to a problem set I was given and noticed that, in finding the expectation value for the momentum operator of a given wavefunction, the following (constants/irrelevant stuff taken out) happened in the integrand:
[tex] \int_{-\infty}^{\infty}\gamma(x)(\hat{p}(\gamma(x))dx = \int_{-\infty}^{\infty}\gamma(x)\frac{\hbar}{i}\frac{\partial}{\partial x}\bigg(\gamma(x)\bigg)dx= \frac{\hbar}{i}\int_{-\infty}^{\infty}\frac{\partial}{\partial(x)}\bigg(\gamma^2(x)\bigg)dx[/tex]
Are we allowed to commute functions of the same dependency on variables into the momentum operator if the momentum operator's differential is w.r.t. that same variable or something? How does this work?
[tex] \int_{-\infty}^{\infty}\gamma(x)(\hat{p}(\gamma(x))dx = \int_{-\infty}^{\infty}\gamma(x)\frac{\hbar}{i}\frac{\partial}{\partial x}\bigg(\gamma(x)\bigg)dx= \frac{\hbar}{i}\int_{-\infty}^{\infty}\frac{\partial}{\partial(x)}\bigg(\gamma^2(x)\bigg)dx[/tex]
Are we allowed to commute functions of the same dependency on variables into the momentum operator if the momentum operator's differential is w.r.t. that same variable or something? How does this work?