# Relation between crystal momentum of the electron and other momentums

1. Nov 19, 2013

### hokhani

As far as I know, $$F_ {ext} = d (\hbar k)/dt = d p_{electron} / dt + d P_{crystal} /dt.$$ could one say that $$\hbar k = P_{electron} + P_{crystal}?$$

2. Dec 2, 2013