You mean of a film, nanoparticles etc...?

Also, can you be more clear about "dispersion curve"?  You mean the dielectric function of the material over different wavelengths?  Or am I misunderstanding?

You can analyze these using the exact same techniques and codes that model waveguides.  Surface waves and guided modes arise due to essentially the same physics.  A very simple technique to implement is the finite-difference method.  I have used this before to model plasmons.  If you want to learn about this method, I created a sequence of lectures on this topic here:

http://emlab.utep.edu/ee5390cem.htm

See Lectures 9-11.  The website has notes and recorded lectures. 

Hope this helps!

Thank you so much for answers mention above ... But just i will declare more about my question, which talked about Nanograting structure so we have prism , metal film layer and grating with metal and shining laser in ATR grating method.

I attached figure describe the structure and result of dispersion graph.

Regarding the tool, i have license of Comsol Multiphysics but  always when i apply structure like in attached file i got some errors in boundary conditions, so you have like one example of applying that on Comsol i will be so grateful.

Thanks

Hello Sherif, transfer matrix method and Fresnel equations are the way to go for the dispersion of metallic layers which you can get the reflection as a function of angle. In terms of the kx as a function of w, you can get them by solving the Maxwell equations.   By the way, have the two 3-D dispersion curves you were showing been published? 

Thank you so much Prof.Raymond Rumpf  for useful information on deliver lectures.

Dear Chuan Zhong , actually i am talking about 3-D dispersion curve and as can you see structure contains 1-D grating, so if you deal with this kind of structure for calculating dispersion ,just inform me.

How to get the surface plasmon dispersion relations of Au/ZnO in comsol?