[Ifeffit] Fwd: Guessed parameter and Einstien temperature

[Scott Calvin]

Hi Abhjeet,

I think you're misunderstanding the meaning of alpha here. It's not  
the temperature expansion coefficient; after all, you're measuring at  
only one temperature.

Generally alpha and thetad should be guessed. For a variety of  
reasons, they are unlikely to be exactly the same as the literature  
values when you fit them. For one thing, the Debye model is just that-- 
a model--and therefore different methods of determining the Debye  
temperature will yield somewhat different results.

As far as the extended parameters Ei, third, and fourth, are you  
saying you'd like to fit them but can't figure out how to do it? Or  
that you're wondering how to set them?

--Scott Calvin
Sarah Lawrence College

On Feb 2, 2009, at 3:32 AM, abhijeet gaur wrote:

>
>
> Hi everyone,
>
> I  am giving artemis the following parameters:
>
>      guess amp  1
>      def  delr  alpha*reff
>      guess enot 0
>      def  ss debye(temp,thetad)
>      set alpha .0002
>      set  thetad  343
>      set  temp    298
>    But I am not getting a very good fit. The value of debye  
> temperature is 343 for Cu( Kittel book)  but I got to know that some  
> persons even guessed the value of thetad as 285+-16 . I am not  
> getting that how we can guess the value of alpha and thetad   . Also  
> I am not getting the value of Ei, 3rd and 4th cumulant in the fit  
> results . So How can I get the value of these parameters in the fit  
> results .
>                                                                                                                                                                  With 
>  thanks
>                                                                                                                                                                   Abhijeet 
>  Gaur
>
> _________