Help with Math in Quantum Mechanics: Variational Method

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In summary, mody2 is seeking help with understanding and obtaining the second equation in the attached photo, which involves the application of the variational method in quantum mechanics. They have provided a link to a paper and are referencing the use of the gamma function. They are asking for assistance in understanding the process and where to start, and are open to any level of explanation.
  • #1
mody mody
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Hello
i read a quantum mechanics part and found a part of mathematics that i am not a familiar with it so i need a help how to get the equation at the bottom of the attached photo (the mathematics of applying variational method )
 

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  • #2
Hello mody2

The one numbered (2) ? Or the one ending in ##\sqrt\alpha## ?
Starting from where ?
What makes you use the term 'variational method' ? Any context ? Where was it mentioned before ?
 
  • #3
i want second equation that ended by root of alpha
starting by just following the sequence given at the photo

that was mentioned here
https://arxiv.org/pdf/1510.07813.pdf
 
  • #5
mody mody said:
starting by just following the sequence given at the photo
I mean where, at what point, at what level, do I have to start ? Do you have any experience at all with a QM course, the hydrogen atom wave functions, the ##Y_{lm}## ? If they are not the 'usual spherical harmonics' to you, I suggest you take a QM textbook and see how far you can come.

Where, exactly, do you get stuck when you work out this <H> ? Show your steps in detail and someone will help you put the last pieces of the puzzle together. Starting from 1+1=2 is really too tedious.
 

1. What is the variational method in quantum mechanics?

The variational method is a mathematical technique used to approximate the ground state energy of a quantum mechanical system. It involves choosing a trial wavefunction and using it to calculate an upper bound for the ground state energy.

2. How is the variational method used in quantum mechanics?

The variational method is used to find an approximate solution for the Schrödinger equation, which describes the behavior of quantum systems. By choosing a trial wavefunction and calculating its energy, we can compare it to the exact energy and improve the accuracy of our approximation by adjusting the wavefunction.

3. What are the advantages of using the variational method in quantum mechanics?

The variational method allows us to obtain an approximation for the ground state energy of a system without solving the Schrödinger equation exactly. This can be useful for complex systems where an exact solution is not possible.

4. Are there any limitations of the variational method in quantum mechanics?

One limitation of the variational method is that it can only provide an upper bound for the ground state energy. Additionally, the accuracy of the approximation depends on the choice of trial wavefunction, which can be difficult to determine for some systems.

5. How is the variational method related to other methods in quantum mechanics?

The variational method is related to other approximation techniques in quantum mechanics, such as perturbation theory and the Hartree-Fock method. It is also closely related to the calculus of variations, a mathematical framework for finding the extreme values of functions.

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