- #1
pmb
There's a problem in Liboff's text "Introductory Quantum Mechanics - 3rd Ed."
On page 176 problem 6.12 states
"A particle moving in one dimension interacts with a potential V(x). In a stationary state of this system show that
(1/2) <x dV/dx > = <T>
where T = p^2/2m is the kinetic energy of the particle."
Liboff gives the answer but starts off with
"In a stationary state,
d<xp>/dt = (i/hbar)<[H,xp]> = 0
..."
Why? I.e. why is d<xp>/dt = (i/hbar)<[H,xp]> = 0 for a stationary state?
Pete
On page 176 problem 6.12 states
"A particle moving in one dimension interacts with a potential V(x). In a stationary state of this system show that
(1/2) <x dV/dx > = <T>
where T = p^2/2m is the kinetic energy of the particle."
Liboff gives the answer but starts off with
"In a stationary state,
d<xp>/dt = (i/hbar)<[H,xp]> = 0
..."
Why? I.e. why is d<xp>/dt = (i/hbar)<[H,xp]> = 0 for a stationary state?
Pete