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(a) Prove the three-dimensional virial theorem

2T=rV

(for stationary states). Hint: Refer to problem 3.31,

(b) Apply the virial theorem to the case of hydrogen, and show that

T=-En;V=2En

(c) Apply the virial theorem to the three-dimensional harmonic oscillator and show that in this case

T=V=En/2

Short Answer

Expert verified

(a) In the case of stationary states ddtrp=0,sorv=2T.

(b) The given expression is verified.

(c) The given expression is verified.

Step by step solution

01

Define virial theorem

The virial theorem connects the gravitational potential energy, U, of a self-gravitating entity to its total kinetic energy, T, which results from the motions of its individual pieces.

The virial theorem connects a quantum system's expected kinetic energy to its potential. This is both theoretically interesting and crucial for computational methods such as "density functional theory."

02

(a) Verification of three-dimensional virial theorem

The three-dimensional virial theorem described as follows,

ddtrp=ihH,rp

It is known that role="math" localid="1658128835661" [H,rp]=i=13[Hj,rjpj]. Apply it to the above expression and then solve it.

ddtr.p=i=13[H,rj]pj+ri=H,pi=i=13p22m+V,rjpj+rjp22mV.pi=i=1312m+P2,ripi+riV.pi=i=1312mj=13pj,pi.ripi+riV,pi

Further evaluate the expression.

ddtr.p=i=1312mj=13(pj,pi.ripipi.ripjpi)+riVi,pi=i=1312mj=13-ihpjpiij-ihpjpi未颈箩+riVi,pi=i=13-1m-ihpjpi+riihVri=ih-P2m+r.V

Further simplify the expression.

ddtrp=H,r.pn=ih.ih-P2m+r.v=r.v+P2m=2T-r.v

Thus, in case of stationary states ddtrp=0,sorv=2T

03

Step 3: (b) Explanation for virial theorem and verification of the given expression

Write the expression in case of hydrogen atom.

Vr=-e40'0rV=e40'0r2r^r.V=e40'0r=-V

So, it can be observed the equation is true but 2T=-V.

It is known that T+V=En'. Substitute the values in this expression.

T+V=EnT-2T=En-T=EnT=-EnV=2En

Thus, the given expression is verified.

04

(c) Verification of the given expression

Write the expression for Harmonic oscillator.

V=12尘蝇2r2V=尘蝇2rr^r.V=尘蝇2r2=2V

Further solve the expression.

2T=2VT=V

It is known that as T+V=En . Substitute the values in this expression.

2T=EnT=V=En2

Thus, the given expression is verified.

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Most popular questions from this chapter

Consider the earth鈥搒un system as a gravitational analog to the hydrogen atom.

(a) What is the potential energy function (replacing Equation 4.52)? (Let be the mass of the earth, and M the mass of the sun.)

V(r)=-e2400,1r

(b) What is the 鈥淏ohr radius,鈥ag,for this system? Work out the actual number.

(c) Write down the gravitational 鈥淏ohr formula,鈥 and, by equating Ento the classical energy of a planet in a circular orbit of radius r0, show that n=r0/ag.From this, estimate the quantum number n of the earth.

(d) Suppose the earth made a transition to the next lower level(n-1) . How much energy (in Joules) would be released? What would the wavelength of the emitted photon (or, more likely, gravitation) be? (Express your answer in light years-is the remarkable answer a coincidence?).

In classical electrodynamics the force on a particle of charge q

moving with velocity through electric and magnetic fields E and B is given

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This force cannot be expressed as the gradient of a scalar potential energy

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(c) In particular, if the fields and are uniform over the volume of the wave packet,

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(a) Using Equation 4.88, work out the first four Laguerre polynomials.

(b) Using Equations 4.86, 4.87, and 4.88, find v(), for the case n=5,I=2.

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Lq(x)=eqq!(ddx)q(e-x-x9)(4.88)v()=Ln-2l+1l-1(4.86)Lqp(x)(-1)pddxLp+q(x)(4.87)cj+1=2(j+l+1-n)(j+1)(j+2l+2)cj(4.76)

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(a) Find鈱﹔鈱猘nd鈱﹔虏鈱猣or an electron in the ground state of hydrogen. Express your answers in terms of the Bohr radius.

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