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1. The Harmonic Oscilloi The harmonic oscillator is probably the simplest and in

ID: 1794778 • Letter: 1

Question

1. The Harmonic Oscilloi The harmonic oscillator is probably the simplest and in some ways the most important ex ample in quantum mechanics. It is the system in which a particle acts as if it were oscillating on a spring: the force that pulls it back to the middle is proportional to the displacement, F =-k(Az). The corresponding potential is simply V(r) = r2 (a) What is the frequency of oscillations for a classical particle with mass m in the (b) Write down the time independent Schrodinger equation for a particle with mass m (c) Show that harmonic oscillator potential above? acted on by the harmonic oscillator potential above is a solution to the time independent Schrodinger equation you wrote down, with enery This solution is not normalized, for simplicity sake.] (d) What is the relationship between the energy above the the classical frequency from part (a)? (e) Write the corresponding solution to the time dependendent Schrodinger equation.

Explanation / Answer

for the given case

F = -k(dx)

V(x) = 0.5kx^2

a. hence frequency of osscilation of classical particle

with mass m in the harmonic potential above is

f = w/2*pi

w = sqroot(k/m)

hence

f = sqroot(k/m)/2*pi

b. Hamiltonian for the case = H

H = p^2/2m + V(x)

p = -ih'd/dx

where h' = h/2*pi

the time independent schrodinger's equation is

-h'^2/2m * d^2(phi(x))/dx^2 + V(x)phi(x) = E*phi(x)

c. consider phi = e^(-sqroot(mk)x^2/2h')

d(phi)/dx = -2x*sqroot(mk)e^(-sqroot(mk)x^2/2h')/2h'

d^(phi)/dx^2 = -2sqroot(mk)e^(-sqroot(mk)x^2/2h')/2h' +4x^2*mk*e^(-sqroot(mk)x^2/2h')/4h'^2

hence

substituting

-h'^2/2m * (-2sqroot(mk)e^(-sqroot(mk)x^2/2h')/2h' +4x^2*mk*e^(-sqroot(mk)x^2/2h')/4h'^2) + 0.5kx^2*e^(-sqroot(mk)x^2/2h') = E*e^(-sqroot(mk)x^2/2h')

-h'/m * (-sqroot(mk)/2 +2x^2*mk/4h') + 0.5kx^2 = E

0.5kx^2 + h'*sqroot(k/m)/2 - 0.5*x^2k = h'*sqroot(k/m)/2 = E

d. E = h'*2*pi*f/2 = hf/2