Valid Solutions for Harmonic Oscillator Potentials

In summary, the given wavefunction \psi(x,0) = N exp[-\alpha(x-a)^2] is a solution to the time-independent Schrödinger equation at time t = 0 for the potential \ V(x) = (1/2)*m\omega^2x^2, where N is a constant and \alpha = m\omega/(2\hbar). To show that the solution is only valid if a = 0, one can plug the wavefunction into the Schrödinger equation and manipulate the resulting equation to show that it is only satisfied when a = 0. If the potential were changed to \ V(x) = (1/2)*m\omega
  • #1
Mohandas
7
0
[tex]\psi(x,0) = N exp[-\alpha(x-a)^2][/tex] is a solution to the time-independent SE at time t = 0 for the potential

[tex]\ V(x) = (1/2)*m\omega^2x^2[/tex]

where N is a constant and [tex]\alpha = m\omega/(2\hbar)[/tex].

I'm asked to show that the solution is valid only if a = 0.

I'm a little at loss as to what strategy i should use to show this.

My initial thought was to somehow exploit the fact that the potential can be expanded in a power series about the origin, and that the solution (for a yet unknown reason) should also be expanded about the origin (and not about 'a'), but it kinda stopped right there..
Of course it might be as easy as just to differentiate (for a=0 and a=constant) the solution and plug it into SE and evaluate the result (in which case, what am i looking for?) ?

Btw, would the solution be valid for any 'a' if the potential was [tex]\ V(x) = (1/2)*m\omega^2(x-a)^2[/tex] ?
 
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  • #2
Mohandas said:
[tex]\psi(x,0) = N exp[-\alpha(x-a)^2][/tex] is a solution to the time-independent SE at time t = 0 for the potential

[tex]\ V(x) = (1/2)*m\omega^2x^2[/tex]

where N is a constant and [tex]\alpha = m\omega/(2\hbar)[/tex].

I'm asked to show that the solution is valid only if a = 0.

I'm a little at loss as to what strategy i should use to show this.

My initial thought was to somehow exploit the fact that the potential can be expanded in a power series about the origin, and that the solution (for a yet unknown reason) should also be expanded about the origin (and not about 'a'), but it kinda stopped right there..
Of course it might be as easy as just to differentiate (for a=0 and a=constant) the solution and plug it into SE and evaluate the result (in which case, what am i looking for?) ?

Btw, would the solution be valid for any 'a' if the potential was [tex]\ V(x) = (1/2)*m\omega^2(x-a)^2[/tex] ?

The obvious thing to do is to simply plug this wavefunction in the time-ind Schroedinger equation and show that the equation is satisfied only if a=0
 
  • #3
Mohandas said:
Of course it might be as easy as just to differentiate (for a=0 and a=constant) the solution and plug it into SE and evaluate the result

Yes, that's what "show that function f is a solution to the differential equation D" means.

(in which case, what am i looking for?) ?

After you plug the function and its derivatives into the differential equation, if the function is in fact a solution, you can cancel everything out (usually after some algebraic manipulation) and end up with 0 = 0.
 
  • #4
Mohandas said:
[tex]\psi(x,0) = N exp[-\alpha(x-a)^2][/tex] is a solution to the time-independent SE at time t = 0 for the potential

[tex]\ V(x) = (1/2)*m\omega^2x^2[/tex]

where N is a constant and [tex]\alpha = m\omega/(2\hbar)[/tex].

I'm asked to show that the solution is valid only if a = 0.

I'm a little at loss as to what strategy i should use to show this.

My initial thought was to somehow exploit the fact that the potential can be expanded in a power series about the origin, and that the solution (for a yet unknown reason) should also be expanded about the origin (and not about 'a'), but it kinda stopped right there..
Of course it might be as easy as just to differentiate (for a=0 and a=constant) the solution and plug it into SE and evaluate the result (in which case, what am i looking for?) ?

Btw, would the solution be valid for any 'a' if the potential was [tex]\ V(x) = (1/2)*m\omega^2(x-a)^2[/tex] ?

Thats right, put it in the time independent schrödinger equation and do the gay maths.. Do you happen to do your home exam in the university in oslo? Me too, i got exactly the same task ^^
 

1. What is a harmonic oscillator?

A harmonic oscillator is a type of physical system that exhibits periodic motion around a stable equilibrium point. It can be described mathematically using the principles of classical mechanics or quantum mechanics.

2. What is the importance of harmonic oscillators in quantum mechanics?

Harmonic oscillators play a crucial role in quantum mechanics as they serve as a model system for understanding the behavior of more complex quantum systems. They also have many real-world applications in fields such as spectroscopy and quantum computing.

3. What is the difference between a classical and quantum harmonic oscillator?

In a classical harmonic oscillator, the position and momentum of the system can have any value and change continuously. In a quantum harmonic oscillator, these properties are quantized and can only have certain discrete values. Additionally, in quantum mechanics, the oscillator's energy is not constant, but rather can fluctuate between different energy levels.

4. How is the energy of a quantum harmonic oscillator related to its frequency?

The energy of a quantum harmonic oscillator is directly proportional to its frequency. This relationship is described by the Planck-Einstein relation, E = hν, where E is the energy, h is the Planck constant, and ν is the frequency of the oscillator.

5. Can the ground state of a quantum harmonic oscillator have zero energy?

No, the ground state of a quantum harmonic oscillator always has a minimum energy value, known as the zero-point energy. This is a consequence of the Heisenberg uncertainty principle, which states that the position and momentum of a particle cannot both be known with certainty at the same time. Therefore, even in its lowest energy state, the oscillator still has some residual energy due to its inherent motion.

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