How to Solve Quantum Mechanics Problems Using Commutation Relations

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The discussion focuses on solving quantum mechanics problems using commutation relations, specifically involving the position operator and Hamiltonian. A user initially struggles with applying the commutation relation but receives guidance on manipulating the equation by multiplying by the energy denominator and inserting the Hamiltonian operator. The conversation reveals a clarification on transforming the position operator into velocity form, which is crucial for the solution. Ultimately, the user successfully resolves their confusion and expresses gratitude for the assistance. The exchange highlights the importance of understanding commutation relations in quantum mechanics problem-solving.
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http://ejokeimg.pchome.com.tw/see-post.html?Flow_No=30201&cat=47&rank="

I try using the commutation relation of the position operator and the Hamiltonian, but failed.:bugeye::bugeye:

Thanks for your kindly help!
 
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By the way, I don't know how to show the pics directly, sorry about that.
 
Multiply the left hand side by the energy denominator. Insert the hamiltonian operator. The commutator trick should then work.
 
StatMechGuy said:
Multiply the left hand side by the energy denominator. Insert the hamiltonian operator. The commutator trick should then work.


Thanks for your reply.^^ You mean like this?
But it's not the original equation. I know that the commutator of position and Hamiltonian is equal to velocity multiplies by
i and hbar(positive or negative sign added). But what I want to know is how to transform the position operator "itself" into the "velocity form" in the first pic I posted. Or my procedure is simply incorrect?
 

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Ooooooooooops, I got through it, thanks for you help!
You are right! No further questions at all...
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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