Menu

Discussion Forum

New Discussion
Filtrer

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Inconsistent Unit in Drude- Lorentz model

Posted 25 juin 2020, 09:55 UTC−4 3 Replies

Noor Nabi Afnan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi,

I am facing inconsistent unit problem while applying Drude- Lorentz model equation for dielectric constant, E - (m^2/(w^2 + i * w * h)) - (f * g^2/((w^2-g^2)+i * k * w)) where E = 5.9673,

w=(2 * 3.1416 * c)/l,

l = 680[nm],

m = 0.022574495298995342[um],

h = 2.9970254723582923[um],

f = 1.09,

g = 0.07339741070532327[um],

k = 0.4550169353125095[um],

c = 3* 10^8 [m/s]

I have converted the unit eV to [um]. Can someone help me out please. Thank You

Attachments:

3 Replies Last Post 27 juin 2020, 06:19 UTC−4
Alexis Prel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 25 juin 2020, 11:12 UTC−4

Hi Noor,

The build-ins constants pi and c_const are available in COMSOL, so you don't have to type approximative values. ;-)

From your file it looks like you applied the following name convention :

m

w

h

f

g

k

But with the expression you put in COMSOl, (m) has the dimension of a frequency, whereas your other variables have the dimension of lengths.

Hi Noor, The build-ins constants `pi` and `c_const` are available in COMSOL, so you don't have to type approximative values. ;-) From your file it looks like you applied the following name convention : \omega_D \to `m` \omega \to `w` \lambda_D \to `h` \Delta\epsilon \to `f` \Omega_L \to `g` \tau_L \to `k` But with the expression you put in COMSOl, \omega_D (`m`) has the dimension of a frequency, whereas your other variables have the dimension of lengths.
Noor Nabi Afnan
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 26 juin 2020, 08:07 UTC−4

Thanks Alexis for your response. I have converted all the value to Hz now. But still comsol is showing the inconsistent unit problem :(

E - (m^2/(w^2 + i * w * h)) - (f * g^2/((w^2-g^2)+i * k * w)) where

E = 5.9673,

f = 1.09,

w = (2 * pi * c)/l [Hz],

m = 2113.6 * 2 * pi * 10^12 [Hz],

h = 15.92 * 2 * pi * 10^12 [Hz],

g = 650.07 * 2 * pi * 10^12 [Hz],

k = 104.86 * 2 * pi * 10^12 [Hz]

Have I done any mistake in writing the equation in comsol?

Thanks Alexis for your response. I have converted all the value to Hz now. But still comsol is showing the inconsistent unit problem :( E - (m^2/(w^2 + i * w * h)) - (f * g^2/((w^2-g^2)+i * k * w)) where E = 5.9673, f = 1.09, w = (2 * pi * c)/l [Hz], m = 2113.6 * 2 * pi * 10^12 [Hz], h = 15.92 * 2 * pi * 10^12 [Hz], g = 650.07 * 2 * pi * 10^12 [Hz], k = 104.86 * 2 * pi * 10^12 [Hz] Have I done any mistake in writing the equation in comsol?

Attachments:

Alexis Prel
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 27 juin 2020, 06:19 UTC−4
Updated: 4 years ago 27 juin 2020, 06:24 UTC−4

Hi Noor, The problem you have now is with the expression of w. When you enter a value directly as for the other parameters you must specify the units, but when the expression is computed from other quantities, the unit will be computed automatically, so you must not put it again. Here the effect of the [Hz] at the end of your expression for w is to multiply l by 1[Hz] in the expression.

If I remove it, I get no unit error from COMSOL. The attached file is exported from the COMSOL interface, you can import it in your model.

Besides the image you attached as an error in the formula, it should read , instead of . Or maybe it is

Hi Noor, The problem you have now is with the expression of `w`. When you enter a value directly as for the other parameters you must specify the units, but when the expression is computed from other quantities, the unit will be computed automatically, so you must not put it again. Here the effect of the `[Hz]` at the end of your expression for `w` is to multiply `l` by 1[Hz] in the expression. If I remove it, I get no unit error from COMSOL. The attached file is exported from the COMSOL interface, you can import it in your model. Besides the image you attached as an error in the formula, it should read \Gamma_L^2, instead of \Gamma_L^{\omega}. Or maybe it is \Gamma_L \cdot \omega

Attachments:

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content