November 28, 2021, 04:45:50 PM
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Topic: Wave function  (Read 18975 times)

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Offline pantone159

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Re: Wave function
« Reply #15 on: June 28, 2008, 01:47:45 AM »
I'm not completely sure about the pointy peak, actually...

That function is *continuous* meaning there is no sudden change in the value anywhere, but the derivative (the slope of the curve) is *discontinuous* as it is sharp up right before the point and sharp down right after (distance zero between these).

I don't know if that is ok or not.

Offline AJFA111

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Re: Wave function
« Reply #16 on: June 28, 2008, 02:34:04 AM »
When you get to the states buy an old Mercedes diesel & fast food it cross country. You'll   love the trip. However you still don't know if Schroedingers' cat is dead(+) or alive{-}. Guess I'll have to ask Hiesenberg.

Offline Astrokel

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Re: Wave function
« Reply #17 on: June 29, 2008, 08:59:38 AM »
well, thanks pantone159 for the reply, i will check with my teacher again(if he does know)

and appreciated others for all your replies  :)
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

Offline Valdorod

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off topic
« Reply #18 on: June 30, 2008, 06:47:22 PM »
probably not the right thread to continue the discussion,

I do remember the ammonium chloride discussion, while the case in the wave function I was obiously and without a doubt way off.  I must admit that I still expect my students to give me ammonia and a hydronium ion as products and consider the chloride ion to be a spectator ion.  Probably just stubborn on that one, definetely do not want to beat a dead horse, so I'll leave it at that.

If you do take that trip, the offer stands for as long as you need it.  By the way El Paso, Texas is just a bridge away from Juarez, Mexico.  Could lead to more interesting places.  ( and no I have never witnessed a donkey show in Juarez)

Valdo


Offline tamim83

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Re: Wave function
« Reply #19 on: July 01, 2008, 11:11:07 AM »
Sorry, I was out of town. 
Wave functions do depend on energy, the more energy the wave has, the more oscilations there are.  Or the more nodes it has (nodes are where the wave function changes sign).  So yes the wave function can change sign as long as this change is smooth and continuous. 

As for your picture; that is a picture of a probability density, which is the square of the wavefuntion (psi2).  The probablility density does not have any negative parts since it is the square of the wavefuction.  You can still see nodes where the wavefuntion changes sign; these just appear as psi2 touches the horizontal axis.  Since psi is smooth and continuous, psi2 should be as well  It still looks pretty smooth to me.  When I say pointy I mean pointy like an "A"
Thanks for all the replies! Im struggling and its rather confusing, however it is part of my syllabus.

tamim83,

1) Wave function is not determined by changes in sign in amplitude but rather energy and it has to be >0 Is this right?

2) I hava attached another graph. Is the wavefunction pointy as you have described? My teacher said it is a wave function as he defined abrupt change in value as + to - and not pointy.

Thanks for being patience!  :)

Offline Astrokel

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Re: Wave function
« Reply #20 on: July 02, 2008, 08:09:30 AM »
hey tamim83,

how do you know the graph is of psi2 and not psi? Because it does not contain any negative part? Why did the y axis of the graph on the question put the symbol psi?

Thanks!!  ;D
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

Offline tamim83

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Re: Wave function
« Reply #21 on: July 02, 2008, 10:01:41 AM »
I saw the same picture in my quantum mechanics class and also more recently in my research group meeting when we discussed time dependent quantum mechanics; it is a probability density.  It is a probability density becase it is all positive and it is an oscillating function.   Nodes mean changes in sign in a wavefunction.  When you square a wavefuction all of the negative portions of the wavefunction become positive. 
« Last Edit: July 02, 2008, 03:26:52 PM by tamim83 »

Offline Astrokel

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Re: Wave function
« Reply #22 on: July 03, 2008, 10:44:00 AM »
thank you so much!
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

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