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phonon wave vector

Posted Sep 20, 2010, 1:25 p.m. EDT Structural Mechanics 6 Replies

Hussein Ayedh
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Hi everyone
it is the first time for me to work on comsol and I want to calculate the phonon modes in nanowire but I don't know how to extract the wave-vectors corresponding to the eigenfrequencies of the phonon modes . and how to export that to matlab. If someone knows about that ,please help me
6 Replies Last Post Jun 11, 2015, 2:18 a.m. EDT
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Hello Hussein Ayedh

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Mike Bifano
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Posted: 1 decade ago Oct 25, 2010, 2:11 p.m. EDT
Have you had any luck? I am interested in this as well.

Have you had any luck? I am interested in this as well.
Seid Mohamadali Sadat
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Posted: 1 decade ago Apr 12, 2012, 2:05 a.m. EDT
hi, could u find out how? I dont know how to define bloch boundary condition in solid mechanics physics.
hi, could u find out how? I dont know how to define bloch boundary condition in solid mechanics physics.
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Apr 12, 2012, 10:28 p.m. EDT
You can manually define a Bloch boundary condition between two boundaries B1 and B2 by applying on boundary B1 a prescribed displacement of the form bndsim1(u)*exp(i*kx*L) where bndsim1() is a boundary similarity operator from Boundary B2. You should also specify that the displacement variables are complex and the Jacobian matrix is Hermetian.

Nagi Elabbasi
Veryst Engineering
You can manually define a Bloch boundary condition between two boundaries B1 and B2 by applying on boundary B1 a prescribed displacement of the form bndsim1(u)*exp(i*kx*L) where bndsim1() is a boundary similarity operator from Boundary B2. You should also specify that the displacement variables are complex and the Jacobian matrix is Hermetian. Nagi Elabbasi Veryst Engineering
Hyunjoon Park
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Posted: 9 years ago May 5, 2015, 6:58 a.m. EDT
I am trying to solve nanowire`s phonon dispersion.

But I have trouble in solving it.

I used 2D axis & 3D circular design. But I can not get satisfied results..
(I used structure mechanics -> solid mechanics & periodic condition.)


I don`t have clue what is problem..
I am trying to solve nanowire`s phonon dispersion. But I have trouble in solving it. I used 2D axis & 3D circular design. But I can not get satisfied results.. (I used structure mechanics -> solid mechanics & periodic condition.) I don`t have clue what is problem..
Daniel Connelly
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Posted: 9 years ago May 6, 2015, 12:28 p.m. EDT
How is a continuum model going to give optical phonon modes? Seems at best you can get only a linear approximation for low-k.
How is a continuum model going to give optical phonon modes? Seems at best you can get only a linear approximation for low-k.
Hyunjoon Park
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Posted: 9 years ago Jun 11, 2015, 2:18 a.m. EDT
I need to solve acoustic phonon modes & some lower optical modes.

If I use continuum model, I can not solve optical modes?

Could I know linear approximation setting method?
I need to solve acoustic phonon modes & some lower optical modes. If I use continuum model, I can not solve optical modes? Could I know linear approximation setting method?

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