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Q: Normalization and Orthogonal ( No Answer,   6 Comments )
Question  
Subject: Normalization and Orthogonal
Category: Science > Physics
Asked by: nikhilr-ga
List Price: $20.00
Posted: 26 Feb 2004 19:48 PST
Expires: 27 Mar 2004 19:48 PST
Question ID: 311276
How do i go about showing that capital psi 2s and capital psi 2px are
normalized?  Orthogonal?
Answer  
There is no answer at this time.

Comments  
Subject: Re: Normalization and Orthogonal
From: bjornsone-ga on 05 Mar 2004 12:50 PST
 
PART 1: Normalizing
A vector is normalized if it has a magnitude of 1.
Calculate the magnitude by taking the square root 
of the sum of the squares of each component  
   Magnitude = sqrt(psi_x*psi_x + psi_y*psi_y + psi_z*psi_z )
This formula for magnitude can be applied to each of your 
vectors to calculate each of their magnitudes.
If this magnitude already has a value of 1 then the vector
has been shown to be normalized.  

If the magnitude is not one, then you can do the following 
to make it normalized:
To normalize a vector just divide the original vector by 
the magnitude (notice that if it is already normalized, then
dividing by 1 won't change the vector)
   normalized x component of psi= psi_x / Magnitude
   normalized y component of psi= psi_y / Magnitude
   normalized z component of psi= psi_z / Magnitude
This method of normalizing can be applied to each of your
vectors if they are not already normalized.

PART 1: Showing Orthogonal
If two vectors are orthogonal, then their dot product will
be zero.
To make the writing here easier I will just show how to
calculate orthogonality on two vectors A and B (you can
substitute in your two psi vectors instead).  Each
vector has an x, y, and z component.  This can be
written as A_x, A_y, and A_z are the three components
of A and that B_x, B_y, and B_z are the three components
of B.
A and B are orthogonal if and only if
A_x*B_x + A_y*B_y + A_z*B_z = 0

If you calculate the left side and you get zero, then you
have shown that the two vectors are orthogonal.
If you don't get zero, then they are not orthogonal.
Subject: Re: Normalization and Orthogonal
From: mathtalk-ga on 05 Mar 2004 12:59 PST
 
Since this is a Physics rather than a Math question, I guessed the
Customer may be asking about electronic orbitals rather than
three-dimensional vectors.  But your definitions for normalization and
orthogonality certainly are correct for the latter context.

-- mathtalk-ga
Subject: Re: Normalization and Orthogonal
From: bjornsone-ga on 05 Mar 2004 19:46 PST
 
Oops, they were probably asking about orbitals.
But there is still a lot of math behind the answer.
If I assume you are dealing with electron orbitals
of a hydrogen atom, the derived eigenfunctions are
expressed in terms of Laguerre Polynomials.  Showing
the orthogonality and normalization of these is 
a rather painful exercise compared to the simple 
vectors that I was originally thinking about.
I hope somebody gives you more details on this proof.
Subject: Re: Normalization and Orthogonal
From: mathtalk-ga on 05 Mar 2004 23:22 PST
 
Actually if you know two functions/vectors are
eigenfunctions/eigenvectors of a self-adjoint operator/symmetric
matrix, corresponding to distinct eigenvalues, then the orthogonality
property is easily established.

Let's sketch the proof for (real) symmetric matrices.  Let u,v be
eigenvalues of a symmetric matrix A:

A = A'

corresponding to distinct eigenvalues:

Au = bu, scalar b

Av = cv, scalar c

with b not equal to c.

Then:

b(u'v) = (u'A)v = u'(Av) = c(u'v)

(b-c)(u'v) = 0

Now since b - c is nonzero, this implies

u dot v = u'v = 0

so u,v are at least orthogonal.

The same idea carries over with minor changes to the eigenfunctions of
self-adjoint operators.  One slight embellishment is the use of
complex arithmetic in the (non-relativistic) Schrödinger equation (a
PDE).

regards, mathtalk-ga


regards, mathtalk-ga
Subject: Re: Normalization and Orthogonal
From: saikiran_r-ga on 18 Mar 2004 00:01 PST
 
Hi,

     I assume that you have the forms of the energy eigenfunctions for
the 2-s and 2-px orbitals. If you dont, these can be obtained by
either looking up some standard book or searching Google :)

     The 2-s orbital has a dependence on the radial coordinate alone
whereas the 2-px orbital depends on the radial coordinate (r) and the
angle theta. The general form of the function is

         psi-2-s  = (constant)*(2-t)*exp(-t/2)
         psi-2-px = (constant)*t*exp(-t/2)*cos(theta)

Normalized or not:
         We know that the abs(psi)-squared gives the probability of
locating an electron at a location. So, if the energy eigenfunction is
normalized, we must have :

           Integral(psi*psi) over all volume = 1.0

Orthogonality:

           Integral(psi1*psi2) over all volume = 0 if (psi1 != psi2)
           that is, integral of product of psi-2s and psi-2px over all volume is 0.

     Hope that helps.


Saikiran
Subject: Re: Normalization and Orthogonal
From: mathtalk-ga on 19 Mar 2004 18:56 PST
 
Hi, Saikiran_r-ga:

Thanks, I think we've lost our original poster, but your Comments were
of interest to me!

regards, mathtalk-ga

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