Dimension of \lambda constant in \delta potential

In summary, the time independent Schroedinger equation in a delta potential with a given constant ##\lambda >0## can be expressed as ##-\frac{\hbar^2}{2m}\frac{d^2}{d x^2}\psi(x)-\lambda \delta(x)\psi(x)=E\psi(x)##. To find the dimension of ##\lambda##, we can use the dimension of ##V(x)## which is given as [V(x)]=ML^2T^{-2} and the one dimensional problem's dimension of ##\psi(x)## which is [\psi(x)]=L^{-\frac{1}{2}}. From this, it can be concluded that the dimension of
  • #1
LagrangeEuler
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Time independent Schroedinger equation in ##\delta## potential ##V(x)=-\lambda \delta(x)##, where ##\lambda >0## is given by
[tex]-\frac{\hbar^2}{2m}\frac{d^2}{d x^2}\psi(x)-\lambda \delta(x)\psi(x)=E\psi(x)[/tex].
How to find dimension of ##\lambda##? Dimension of ##V(x)## is
[tex][V(x)]=ML^2T^{-2}[/tex].
Because it is one dimensional problem dimension of ##\psi(x)## is
[tex][\psi(x)]=L^{-\frac{1}{2}}[/tex].
Is then also
[tex][\delta(x)]=L^{-\frac{1}{2}}[/tex]?
 
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  • #2
The dimension of ##\psi## is irrelevant. From ##\int dx\,\delta(x)=1## it follows that the dimension of ##\delta## is ##L^{-1}##. From that, the dimension of ##\lambda## should be easy.
 
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  • #3
Demystifier said:
The dimension of ##\psi## is irrelevant. From ##\int dx\,\delta(x)=1## it follows that the dimension of ##\delta## is ##L^{-1}##. From that, the dimension of ##\lambda## should be easy.
Thank you very much.
 
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What is the dimension of the lambda constant in a delta potential?

The dimension of the lambda constant in a delta potential is energy per length cubed, or [E][L]^-3. This is because the potential is a function of the distance between particles, which has units of length.

How does the dimension of lambda affect the behavior of the delta potential?

The dimension of lambda affects the strength of the potential, with a larger lambda leading to a stronger potential. This can result in different behaviors such as bound states or scattering depending on the value of lambda.

Can the dimension of lambda be negative?

No, the dimension of lambda cannot be negative. It must have units of energy per length cubed in order for the potential to have physical meaning.

What is the relationship between the dimension of lambda and the dimension of the delta function?

The dimension of lambda is related to the dimension of the delta function by [L]^-3 = [L]^-1 * [E]^-1, where [L]^-1 is the dimension of the delta function and [E]^-1 is the dimension of the lambda constant.

How does the dimension of lambda change in different dimensions?

The dimension of lambda remains the same in different dimensions, as it is a physical constant. However, the behavior of the delta potential may change in different dimensions due to the different scaling of length and energy units.

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