budullewraagh Posted October 25, 2007 Posted October 25, 2007 Does anyone know where I can find integral tables for QM? I tried a few, but they cannot be solved as indefinite integrals that give rise to noninfinite quantities. Example: [math] r=\int_{0}^{\infty} (&\X\Psi*(x))(&\X\Psi(x))*4*&\X\pi*r^2*dr [/math] <r>=(integral, 0 to infinity) (psi(x))*(psi*(x))dr Using integration by parts gives a solution that goes to infinity. Can anyone help me find some tables? Thanks, Clark
NeonBlack Posted October 25, 2007 Posted October 25, 2007 Most of the integrals in basic QM shouldn't require a table. What exactly is the psi function you are working with? I see 1 problem and 1 potential problem. Problem: If you want the average r, you need [math]\int r \Psi^2dr[/math] Potential Problem: I notice you aren't diving by [math]\int \Psi^2dr[/math] If psi is normalizable and already normalized, then you don't need to do this. So in general, this is what you want: [math]<r>=\frac{\int r \Psi^2 dr}{\int \Psi^2 dr}[/math]
swansont Posted October 25, 2007 Posted October 25, 2007 CRC handbook has integral tables. I like Dwight, Table of Integrals and Other Mathematical Data, though my edition didn't have a gaussian integral in it (!). Of course, you can compile your own list as you find solutions, and find them on the intertubes. http://en.wikipedia.org/wiki/Table_of_integrals http://integral-table.com/IntegralTable.pdf (<—— pdf) http://www.math.unb.ca/sections/integrals/
BenTheMan Posted October 26, 2007 Posted October 26, 2007 budullewraagh--- you need a position or momentum space representation for psi. Then you can do the integrals at integrals.com. Actually, if you are a physics udergrad, you should own a copy of this book. Seriously. If you go to grad school, you may eventually need this book.
budullewraagh Posted November 9, 2007 Author Posted November 9, 2007 Yeah, I apologize; the latex didn't work out for me. Actually, the integral I was looking for was available at sosmath.com; I was computing an expectation value for the radius of the He+ cation for my physical chemistry course. Thanks anyway for your help!
ajb Posted November 9, 2007 Posted November 9, 2007 Something similar I have wanted is a list of the classes of potentials that the Schrödinger equation is exactly solvable in the sense that the wave function can be written in terms of elementary and special functions. I imagine that the list is not huge. Anybody seen such a list?
Norman Albers Posted November 16, 2007 Posted November 16, 2007 Here's a little more LaTex: [math] \int_0^\infty dr \Psi^*\Psi [/math] or maybe if angular integrations are not yet done, [math] \int d^3V \Psi^* \Psi [/math]. You don't want to hear my attitude toward normalization! I have spoken here: http://www.scienceforums.net/forum/showthread.php?t=24832&highlight=normal+modes .
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