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Schroedinger Poisson

Posted 13.07.2011, 02:29 GMT-4 Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.0, Version 4.2a 1 Reply

Alexandre Fête
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Good morning,
I have a very simple question about building my model however after looking quite a lot on the internet I was not able to find the solution so... sorry if it's trivial :-)

I have a comsol model were I first solve the Schroedinger equation in a triangular potential well. Thus at the end of this calculation the variable ("u") is solved for a serie of eigenvalues. This works fine..

Then I want to use let's say the three first eigenvectors to compute this :

(with(1,u*conj(u))+with(2,u*conj(u))+with(3,u*conj(u)))/epsilon

with epsilon a constant.

This expression seems to be correct since I can plot it in comsol. However if I introduce this expression in the source term of the poisson equation it doesn't work..is there any other way to specifiy to comsol that I want the electron density term in the poisson equation to be defined as the sum of the three first solution ?

If you need I can upload my model..

Thanks a lot
Alex
1 Reply Last Post 24.04.2014, 14:23 GMT-4
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Hello Alexandre Fête

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Josep Planelles
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Posted: 1 decade ago 24.04.2014, 14:23 GMT-4

Good morning,
I have a very simple question about building my model however after looking quite a lot on the internet I was not able to find the solution so... sorry if it's trivial :-)

I have a comsol model were I first solve the Schroedinger equation in a triangular potential well. Thus at the end of this calculation the variable ("u") is solved for a serie of eigenvalues. This works fine..

Then I want to use let's say the three first eigenvectors to compute this :

(with(1,u*conj(u))+with(2,u*conj(u))+with(3,u*conj(u)))/epsilon

with epsilon a constant.

This expression seems to be correct since I can plot it in comsol. However if I introduce this expression in the source term of the poisson equation it doesn't work..is there any other way to specifiy to comsol that I want the electron density term in the poisson equation to be defined as the sum of the three first solution ?

If you need I can upload my model..

Thanks a lot
Alex


I have checked that if you introduce with(1,u*conj(u)) it does work.
However, with(2,u*conj(u)) does not, because only the first eigenvector
is stored in solution 1 ... I do not know yet to store all eigenvectors
in this solution 1
jp

[QUOTE] Good morning, I have a very simple question about building my model however after looking quite a lot on the internet I was not able to find the solution so... sorry if it's trivial :-) I have a comsol model were I first solve the Schroedinger equation in a triangular potential well. Thus at the end of this calculation the variable ("u") is solved for a serie of eigenvalues. This works fine.. Then I want to use let's say the three first eigenvectors to compute this : (with(1,u*conj(u))+with(2,u*conj(u))+with(3,u*conj(u)))/epsilon with epsilon a constant. This expression seems to be correct since I can plot it in comsol. However if I introduce this expression in the source term of the poisson equation it doesn't work..is there any other way to specifiy to comsol that I want the electron density term in the poisson equation to be defined as the sum of the three first solution ? If you need I can upload my model.. Thanks a lot Alex [/QUOTE] I have checked that if you introduce with(1,u*conj(u)) it does work. However, with(2,u*conj(u)) does not, because only the first eigenvector is stored in solution 1 ... I do not know yet to store all eigenvectors in this solution 1 jp

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