- #1
IFNT
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If I have [tex]H=p^2/2m+V(x)[/tex], [tex]|a'>[/tex] are energy eigenkets with eigenvalue [tex]E_{a'}[/tex], isn't the expectation value of [tex][H,x][/tex] wrt [tex]|a'>[/tex] not always 0? Don't I have that
[tex]<a'|[H,x]|a'> = <a'|(Hx-xH)|a'> = <a'|Hx|a'> - <a'|xH|a'> = 0 [/tex]?
But if I calculate the commutator, I get:
[tex]<a'|[H,x]|a'> = <a'|-i p \hbar / m|a'> \neq 0 [/tex]
I suddenly can't see where I did wrong...
[tex]<a'|[H,x]|a'> = <a'|(Hx-xH)|a'> = <a'|Hx|a'> - <a'|xH|a'> = 0 [/tex]?
But if I calculate the commutator, I get:
[tex]<a'|[H,x]|a'> = <a'|-i p \hbar / m|a'> \neq 0 [/tex]
I suddenly can't see where I did wrong...