# Ehrenfest theorem

Might be trivial, but: In deriving it, I don't understand how the minus sign comes in to establish the [H,A] commutator. (it seems to me that both partial derivatives of ψ should come out positive)
For example, in
http://www.tcm.phy.cam.ac.uk/~bds10/aqp/handout_operator.pdf
on page 5.

dextercioby
Homework Helper
Search for the G. Frieseke's article on arxiv.org. That's the proof for general self-adjoint operators.

Lol, those are my lecture notes.

The minus sign is there because you have the i inside the bra and so when you take its complex conjugate you get a -i.

Lol, those are my lecture notes.

The minus sign is there because you have the i inside the bra and so when you take its complex conjugate you get a -i.

right... Thanks!