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(a) Construct the wave function for hydrogen in the state n=4,I=3,m=3. Express your answer as a function of the spherical coordinates r,and.

(b) Find the expectation value of role="math" localid="1658391074946" rin this state. (As always, look up any nontrivial integrals.)

(c) If you could somehow measure the observable Lx2+Ly2on an atom in this state, what value (or values) could you get, and what is the probability of each?

Short Answer

Expert verified

(a) The wave function for hydrogen in the given states is

433=-16144a9r3e-r/4asin3()e3i.

(b) The expectation value in the state is 18a.

(c ) The value is32 .

Step by step solution

01

Define the wave function

The location of an electron at a specific place in space (defined by its x, y, and z coordinates) and the amplitude of its wave, which corresponds to its energy, are related by a mathematical function known as a wave function,.

02

Step 2: (a) Construct the wave function for hydrogen

The equation for the spatial wave function of a hydrogen atom ,

n/m=2na3n-I-1!2nn+I!3e-r/na2rnaILn-I-12I+12rnaYIm,

HereL is an associated Laguerre polynomial andY is a spherical harmonic, and they are given as follow:

Lpqx=c0j=0p-1jp+q!p-j!q+j!j!xjYIm,=2I+1I-m!4I+m!-1/2eimoPImcos

HerePImis the associated Legendre function:

Plm(x)=(1-x2)m/2ddx|m|Pl(x)

And,

Pl(x)=12ll!ddxI(x2-1)l

For n=4,I= 3 and m =3, determine Y33. To find it construct YII

Yll=(-1)I(2l+1)412I!eilPll(cos())

From (1), writePIIas:

Pll(x)=(1-x2)1/2ddxIPl(x)

Replace from (5) with PI

Pll(x)=12ll!(1-x2)I/2ddx2I(x2-1)l

but (x2-1)l=x2I+, and the remaining term has a power less than 2I.So, when differentiate (x2-1)l,2ltimes all the terms vanishes except the first term with the power of , thus:

Pll(x)=12ll!(1-x2)I/2ddx2x2I

Now,

ddxnxn=n!

Hence:

Pll=(2l)!2ll!(1-x2)I/2

Next for x=cos(),1-x2=sin2():

Pll=(2l)!2ll!sinl()

So:

YII=-1I2I+142I!eiI2I!2II!sini=-1I2I!2I+14eiI12II!sinI=1I!2I+1!4-12eisinI

Again, forI=3,

y33=-356412sin3e3i

Also, for n=4,l=3and m=3, use L07(x)=7!=5040.Substitute L07(x)andY33into the overall formula (1),

localid="1658397501310" 433=12a31650403e-r/4ar2a35040-356412sin3e3i=-16144蟺补9r3e-r/4asin3e3i433

Therefore, the wave function for hydrogen in the given states as a function of the spherical coordinatesr,and=-16144蟺补9r3e-r/4asin3e3i433is .

03

(b) Determine the expectation value of r

Evaluate the expectation value ofr, that is r, as:

localid="1658403974750" r=r2d3r=161442蟺补9rr6e-r/2asin6r2sindrdd=161442蟺补90r9e-r/2a0d02d=161442蟺补99!2a1021.4.63.5.72

Further evaluate and get,

=18ar=18a

Thus, the expectation value of r in the state is 18a.

04

(c) Find the probability.

Assume thatbe an eigen function of the operator with eigen value of l(l+1)2,forI=3

Thus:

L2=II+12=122

Supposerole="math" localid="1658398355830" 433be an eigen function of the operator Lzwith eigen value of mtform=3,:

Lz=3

Hence:

role="math" localid="1658398913271" Lx2+Ly2=L2-Lz2=122-92=32=32

Thus, the required value is32

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Most popular questions from this chapter

The electron in a hydrogen atom occupies the combined spin and position stateR211/3Y10++2/3Y11-

(a) If you measured the orbital angular momentum squared L2, what values might you get, and what is the probability of each?

(b) Same for the component of orbital angular momentum Lz.

(c) Same for the spin angular momentum squaredS2 .

(d) Same for the component of spin angular momentum Sz.

Let JL+Sbe the total angular momentum.

(e) If you measureddata-custom-editor="chemistry" J2 , what values might you get, and what is the probability of each?

(f) Same forJz .

(g) If you measured the position of the particle, what is the probability density for finding it atr , , ?

(h) If you measured both the component of the spin and the distance from the origin (note that these are compatible observables), what is the probability density for finding the particle with spin up and at radius ?

A particle of mass m is placed in a finite spherical well:

V(r)={-V0,ra;0,r>a;

Find the ground state, by solving the radial equation withl=0. Show that there is no bound state if V0a2<2k2/8m.

Use equations 4.27 4.28 and 4.32 to construct Y00,Y21Check that they are normalized and orthogonal

a) Check that the spin matrices (Equations 4.145 and 4.147) obey the fundamental commutation relations for angular momentum, Equation 4.134.

Sz=h2(100-1)(4.145).Sx=h2(0110),sy=h2(0-ii0)(4.147).[Sx,Sy]=ihSz,[Sy,Sz]=ihSx,[Sz,Sx]=ihSy(4.134).(b)ShowthatthePaulispinmatrices(Equation4.148)satisfytheproductrulex(0110),y(0-ii0),z(100-1)(4.148).jk=jk+io'IjklI,(4.153).

Wheretheindicesstandforx,y,orz,ando'jklistheLevi-Civitasymbol:+1ifjkl=123,231,or2=312;-1ifjkl=132,213,or321;otherwise.

Use separation of variables in Cartesian coordinates to solve infinite cubical well

V(x,y,z)=0if x,y,z are all between 0 to a;

V(x,y,z)=Otherwise

a) Find the stationary states and the corresponding energies

b) Call the distinct energies E1,E2,E3,..in the order of increasing energy. Findlocalid="1658127758806" E1,E2,E3,E4,E5,E6determine their degeneracies (that is, the number of different states that share the same energy). Comment: In one dimension degenerate bound states do not occur but in three dimensions they are very common.

c) What is the degeneracy of E14 and why is this case interesting?

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